Small Arms Make Safe Procedure for the Recovery of Fingerprint Evidence Draft 5

Forensic Modular Masters
MATTHEW PERRYMAN
Small Arm ‘Make Safe’ procedure for the preservation of
Fingerprint Evidence
Cranfield Defence and Security
MSc Thesis
July 2013

1
Matthew Perryman FMM-2013
DISCLAIMER
This report was written by a student on the Forensic Modular
Masters programme at Cranfield Defence and Security, of
Cranfield University in Shrivenham. It has not been altered or
corrected as a result of assessment and it may contain errors and
omissions. The views expressed in it, together with any
recommendations are those of the author and not of the
Defence Academy College of Management & Technology,
Cranfield Defence and Security, or any individual member of
staff. This document is printed on behalf of the author by the
College, but it has no official standing as an MOD or College
document.

2
CRANFIELD UNIVERSITY
CRANFIELD DEFENCE AND SECURITY
DEPARTMENT OF ENGINEERING & APPLIED SCIENCE
Forensic Modular Masters THESIS
Academic Year: 2012-2013
Matthew Joe Perryman
Small Arm ‘Make Safe’ procedure for the preservation of
Fingerprint Evidence
Supervisors: Mr Stephen Champion and Dr James Shackel
July 2013
This thesis is submitted in partial fulfilment of the
requirements for the Degree of Master of Science.
© Cranfield University 2013. All rights Reserved. No part of this publication may be
reproduced without the written permission of the copyright holder.

3
ABSTRACT
Currently only 15% of small arms recovered provide usable fingerprint evidence and
only one case in the past 20 years had revealed a viable DNA sample. It is the opinion
of NABIS that this is due to the ‘make safe’ procedure used by firearms teams when
recovering weapons from the crime scene. It is not the intent of this project to critique
the current make safe practice but to establish the conditions that make fingerprint
recovery problematic from various parts of the gun, both internally and externally. Thus
leading to a list of recommendations that should be taken into account when developing
a make safe procedure. Both safety and evidence recovery will be of consideration

4
ACKNOWLEDGMENTS
I would like to thank:
My Project leaders Stephen Champion for guiding me throughout this project, his
assistance was greatly appreciated, Dr. James Shackel for advising me on areas such as
superglue fuming and the safety protocols associated with the technique.
Without it this project would not be the piece of work it is today
Dr. Karl Harrison for his invaluable advice regarding how to develop the
fingerprints in question and the recovery of them.
Adrian Mustey For his assistance not only in procuring the equipment needed
for me to complete this work but also assisting me in the actual work it self
Lt Col (Ret). John Starling, WO2 Martyn Arthur, Mr. Phil Harding For
allowing me access to the armoury of the Defence Academy of the United Kingdom and
passing on their extensive knowledge regarding, the use, manufacture and history of the
firearm. Also for allowing me to use firearms from their impressive collection.
Dave ‘Bomber’ Harris, Jim Clements, Paul Walker, Mick Warden and Graham
Creighton from ASET for allowing me to sit on their weapons handling lectures and
providing me with photographs and information regarding the firearms I used.
The staff at Manlove Forensics, especially Neil Tonglle and John Manlove for
allowing the use of their cyanoacrylate fuming facilities, allowing me to complete a
larger majority of the experimental part of the thesis.
I would also like to thank my tutor, Dr. Peter Zioupos for urging me forwards
during times of difficulty.

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Contents
ABSTRACT ..................................................................................................................... 3
ACKNOWLEDGMENTS................................................................................................ 4
ABBREVIATIONS.......................................................................................................... 8
Chapter 1: INTRODUCTION .......................................................................................... 9
1.1 Background............................................................................................................. 9
1.2 Forensic Relevance of Paper................................................................................... 9
1.3 Project Aims ......................................................................................................... 10
1.4 Make Safe Procedures .......................................................................................... 10
1.5 General Fingerprint Recovery and Enhancement Methods.................................. 11
Chapter 2: LITERATURE REVIEW ............................................................................. 14
2.1 Introduction........................................................................................................... 14
2.2 Background........................................................................................................... 14
2.3 Why are Fingerprints important?.......................................................................... 14
2.4 Anatomy of the Fingerprint .................................................................................. 18
2.4.1 Anatomy of the Skin.......................................................................................... 18
2.4.2 Friction Ridges................................................................................................... 20
2.5 Problems Associated with Latent Print Recovery on Firearms ............................ 23
2.5.1 Life of Latent Prints ....................................................................................... 23
2.5.2 Environmental Conditions.............................................................................. 24
2.5.3 Processing Problems ...................................................................................... 25
2.6 Materials used in Firearm Manufacture................................................................ 27
2.6.1 Metals............................................................................................................. 27
2.6.2 Woods............................................................................................................. 29
2.6.3 Polymers......................................................................................................... 31
2.7 Places where Fingerprints can be found on a Firearm and Make Safe Procedures
.................................................................................................................................... 32
2.7.2 Pistols ............................................................................................................. 32
2.7.3 Revolvers........................................................................................................ 35
2.8 Possible Encountered Substrates .......................................................................... 45
2.8.1 Smooth Non-Porous Materials....................................................................... 49

6
2.8.2 Rough Non-Porous Materials......................................................................... 50
2.8.3 Vinyl, Rubber and Leather............................................................................. 51
2.8.4 Metals............................................................................................................. 52
2.8.5 Woods............................................................................................................. 53
2.8.6 Fabrics............................................................................................................ 54
2.9 Fingerprint Development Methods and Reagents ................................................ 55
2.9.1 Visual Examination........................................................................................ 55
2.9.2 Fluorescence Examination ............................................................................. 55
2.9.3 Gentian Violet ................................................................................................ 57
2.9.4 Ninhydrin/DFO .............................................................................................. 57
2.9.5 Physical Developer......................................................................................... 60
2.9.6 Powders.......................................................................................................... 61
2.9.7 Radioactive Sulphur Dioxide ......................................................................... 63
2.9.8 Solvent Black 3 .............................................................................................. 63
2.9.9 Superglue........................................................................................................ 64
2.10 Make Safe Procedures......................................................................................... 66
2.10.1 ASET Method .............................................................................................. 66
Chapter 3: METHODOLOGY AND METHODS ......................................................... 70
3.1 Methodology......................................................................................................... 70
3.2 Experimental Design............................................................................................. 73
3.3 Powder Visualisation ............................................................................................ 75
3.4 Chemical Visualisation......................................................................................... 75
3.4 Recovery Methods ................................................................................................ 76
3.6 Classification and Comparison ............................................................................. 78
Chapter 4: RESULTS..................................................................................................... 81
4.1 Control Fingerprints.............................................................................................. 81
4.2 Before Make Safe Procedures............................................................................... 83
4.2.1 Powder Development..................................................................................... 83
4.2.2 Cyanoacrylate Fuming ................................................................................... 86
4.3 After Make Safe Procedures ................................................................................. 88
4.3.1 Powder Development .................................................................................... 88

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4.4 Final Comparison.................................................................................................. 93
Chapter 5: DISCUSSION............................................................................................... 95
5.1 The Results ........................................................................................................... 95
5.1.1 Powder Development..................................................................................... 95
5.2 Critique of the Experimental Method ................................................................. 100
5.3 Discussion of the ASET Method ........................................................................ 103
5.4 Further Work....................................................................................................... 106
Chapter 6: CONCLUSION........................................................................................... 111
REFERENCES............................................................................................................. 113
GLOSSARY................................................................................................................. 121
APPENDIX 1 ............................................................................................................... 126
LIST OF FIGURES...................................................................................................... 133
LIST OF TABLES ....................................................................................................... 135

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ABBREVIATIONS
 DNA – Deoxyribonucleic Acid, a self-replicating material present in nearly all
living organisms as the main constituent of chromosomes.
 CAST – Centre of Science and Technology
 SWGFRAST - Scientific Working Group on Friction Ridge Analysis, Study and
Technology
 B.C. – Before Christ
 A.D. – Anno Domini
 MIM – Metal-injection-moulding, a metalworking process where finely-
powdered metal s mixed with a binder material and then injected into a mould to
create a specific shape or component.
 mm – millimetre, 1/1000 of a metre
 g – gram, 1/1000 of a kilogram
 ASET – Ammunition Systems and Explosive Technology
 BBC Check – Breech, Body, Chamber Check
 PPE – Personal Protective Equipment
 CNA - Cyanoacrylate
 ACP – Automatic Colt Pistol
 PDT – 3-(2-pyridyl)-5, 6-diphenyl-1-2-4-triazine
 AFIS – Automated Fingerprint Identification System
 ESDA – Electrostatic Document Apparatus

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Chapter 1: INTRODUCTION
1.1 Background
Whether at a scene collecting evidence or whether reviewing certain items within a
laboratory the examiner of that scene or evidence is looking for one thing, data. Data to
prove or refute a hypothesis that the person conducting the investigation has deduced
based on prior knowledge of the scenario that led to the investigation. The data obtained
can vary greatly depending on the evidence type, primarily when that evidence is
biological in nature, especially bodily fluids from a human source that data also holds
the potential for the identification of persons who were possibly at the scene or linked to
it through third parties or independent scenarios. With the technological advancement of
DNA collection and analysis, and also with its strong backing in the practical and
academic scientific community it is one of more trusted forms of human identification1
.
One form of identification that is generally not as popular but still just as important as it
used to be is the Fingerprint.
1.2 Forensic Relevance of Paper
The general forensic relevance of this project is in deducing whether ‘Make Safe’
procedures mar fingerprint evidence left on firearms and also whether that affects the
recovery and identification of said evidence.
All forensic practices must be researched scientifically, peer reviewed and scrutinised,
and this allows evidence to be considered as sound and sufficiently robust for court-
room and legal use.
The more specific forensic relevance of this project is that the results obtained will be
communicated to the forensic community who then, dependant on the outcome of

10
experimentation, wish to adapt, utilise, contradict or review the results obtained during
the experimentation in field.
1.3 Project Aims
 To investigate whether ‘Make Safe’ procedures of small arms contaminate
possible fingerprint evidence on the firearm.
 To investigate which visualisation methods are suitable for small arms.
 To investigate whether the component materials of firearms interfere with the
development and recovery of fingerprints
1.4 Make Safe Procedures
A ‘make safe’ procedure is a series of actions preformed to render a firearm at a scene
safe to handle. This takes priority over the collection of any evidence associated with
the firearm due to the fact that when confronted at the scene it is difficult to tell whether
the firearm is safe to handle. Rendering a firearm safe should be one of the higher
priorities for the scene manager and principal investigation as mistakes can be made,
and mistakes with firearms can ultimately end up with the serious injury or death of an
individual, turning what would be a routine firearms investigation into a much more
serious case.
Most ‘make safe’ procedures will be undertaken by an individual trained in the
safe handling of firearms, and even though most types of firearms can be made safe in
the same way the actual procedure will differ from country to country and even from
force to force.
It is common for firearms or similar types to have ‘make safe’ procedures that are also
similar, i.e. most types of Semi-Automatic Handguns will have a similar procedure as
will most types of Revolvers.

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1.5 General Fingerprint Recovery and Enhancement Methods
When encountering fingerprints or any friction ridge impression left on surfaces, they
are generally divided into two classes; visible and latent (invisible to the naked eye).
Visible fingerprints tend to be seen when the print has been imprinted into a soft
medium or the finger is stained with a residue which allows the fingerprint to become
visible, e.g. blood, but also sometimes the medium onto which the fingerprint is placed
aides with this. Fingerprints left on glass tend to be visible without any other
techniques. Latent marks on the other hand require further examination and the
application of visualisation tools, the most common tools and techniques being;
 Artificial light sources
 Powder enhancement
 Chemical enhancement
Initially when searching for latent fingerprints a good source of artificial light is
most helpful also exploiting different angles will allow fingerprints to be visualised
easier. Occasionally an item with a suspected fingerprint may need to be moved, if this
is the case it must be done with care as not to mar the print. Once prints have been
found then enhancement can begin, generally on a scene or in a lab the first point of call
usually is powder enhancement.
Powders are generally flake or granular, the powder is applied with a fine animal
hair brush or specialist fingerprint brushes and rather than brushing the powder is
sprinkled onto the print gently, the powders then adhere to the secretions in the print
making it visible for photography and recovery.
Flake Powders came into general use in the 1970’s in a variety of metals (Aluminium,
Bronze and Gold). Magnetic powders are also available for extremely smooth or

12
laminated surfaces such as surfaces of a firearm and the magazines associated with that
firearm. Dependant on the substrate material or surface, there are multiple development
and visualisation methods available as shown in Table 1.
Type of
Development
Method/s
Name of
Method/s
Details
Fluorescence
Laser or
Ultraviolet
Visualises certain chemical constituents by
exploiting their natural fluorescence, sample is
viewed with short wave length electromagnetic
radiation and then viewed through specific
filters.
Powder
Exactly the same as Laser or Ultraviolet but first
requires a fluorescent powder to be dusted onto
to the print.
Chemical
Exactly the same as Laser or Ultraviolet but
requires a chemical development before
visualisation
Powders
Powders
Adheres to the fatty deposits in sweat, comes in a
variety of different types and colours, for use on
differing substrate surfaces and to allow visual
contrast
Magnetic
Powders
Ferromagnetic Powders used in the same way as
conventional powders but due to the their
magnetic qualities allows for less waste as the
user determines the amount to be removed from
the brush during the dusting procedure
Fluorescent
Used in the same way as conventional powders
but fluoresce under specific lighting conditions
allowing for ease of photography
Chemical Chemical
Usually exploits a colour change in the sweat
located within the fingerprint for easier
visualisation
Table 1: Table briefly describing core methods of Fingerprint Development, all information taken
from2
Powder dusting is the simplest and most commonly used procedure, it is also the oldest
technique and does not require special training or specialist equipment 3
.

13
Chemical Development, primarily is restricted to a laboratory, the Home Office
Centre of Science and Technology (CAST) of Stanbridge, England have various set
methods of enhancing fingerprints chemically, one example; which is especially
advantageous when dealing with porous material is superglue fuming another method is
vacuum metal deposition but there are many techniques available 4,5
.
Recovery is usually carefully transferring the print onto adhesive tape6
, however
this is not the only method in the 1930’s a technique using gelatine coated photographic
paper for print recovery was pioneered7
.

14
Chapter 2: LITERATURE REVIEW
2.1 Introduction
In Forensic based literature, particular in the separate fields of fingerprinting and of
firearms investigation there is a multitude of information but unfortunately when the
two fields are combined the amount of available literature diminishes. The following
literature will analyse all the fundamental aspects of this research project in detail, as an
introduction to the research itself.
2.2 Background
The Principle upon which all modern forensic science is based, is Locard’s Principle –
which is founded upon the concept that every contact leaves a trace8
. The research into
fingerprint visualisation and recovery is no exception to this concept. The core idea is
that any surface an individual touches leaves a physical, measurable trace of themselves.
It is well documented that fingerprints can be extremely persistent lasting for
years on a variety or surfaces9–11
.
2.3 Why are Fingerprints important?
Fingerprints, the inescapable mark of identity left from the palms of the hands and the
soles of the feet of an individual. This is why fingerprints are one of the oldest and most
important evidence categories in forensic science. The use of fingerprints as a means of
identification has reached a point where it is accepted as an article of faith by the
general public and is almost universally accepted in forensics and other sciences as a
solid form of evidence type, though contention does appear when looking at fingerprints
from a statistical viewpoint.

15
When looking at research conducted by Cole12
and Langenburg13
, they both
looked at fourteen statistical methods proposed by other experts in the fielda
and in
conjunction with work conducted by Stoney14
, they concluded from an entirely
statistical viewpoint, fingerprint evidence is incredibly weak and must be addressed but
Cole also mentioned that generally the opinion of the expert witness is enough as they
have based their hypothesis on the experience of their peers and the data recovered from
previous case studies.
a
The Galton Model94
, The Henry Model95
, The Balthazard Model96
, The Bose Model97
, The Locard
Model98
, The Wilder and Wentworth Model99
, The Pearson Model100
, The Cummins & Midlo Model101
,
The Amy Model102
, The Trauing Model103
, The Gupta Model104
, The Ostenburg Model105
, The Stoney-
Thorten Model106
and the Champod-Margot Model107
.

16
Probability of Matching a Specific Configuration of:
Author and Year 36 Minutiae 12 Minutiae 8 Minutiae
Galton (1892) 1.45 x 10-11
9.54 x 10-7
6.06 x 10-6
Henry (1900) 13.2 x 10-23
3.72 x 10-9
9.54 x 10-7
Balthazard (1911) 2.12 x 10-22
5.96 x 10-8-
1.53 x 10-5
Bose (1917) 2.12 x 10-22
5.96 x 10-8-
1.53 x 10-5
Wilder and
Wentworth (1918)
6.87 x 10-62
4.10 x 10-21
2.56 x 10-14
Pearson (1930) 1.09 x 10-41
8.65 x 10-17
1.22 x 10-12
Roxburgh (1933) 3.75 x 10-47
3.35 x 10-18
2.24 x 10-14
Cummins and
Midlo (1943)
2.22 x 10-63
1.32 x 10-22
8.26 x 10-16
Trauing (1963) 2.47 x 10-26
2.91 x 10-9
2.04 x 10-8
Gupta (1968) 1.00 x 10-38
1.00 x 10-14
1.00 x 10-10
Osterburg et al.
(2001)
1.33 x 10-27
3.05 x 10-15
3.50 x 10-13
Stoney and
Thornton (1985 –
1989)
1.20 x 10-80
3.50 x 10-15
3.50 x 10-13
Pankati et al.
(2001)
5.47 x 10-59
1.22 x 10-20
1.56 x 10-14
Amy (1946-1948) 6.2 x 10-18
3.4 x 10-14
1.8 x 10-8
Kingston (1964) 3.90 x 10-97
3.74 x 10-32
1.97 x 10-20
Champod (1995-
1996)
Two Configurations
5 Ridge Endings, 2
Bifurcations
2.5 x 10-5
3 Ridge Endings, 1
Enclosure, 1 Spur
and 1 opposed
Bifurcation
7 x 10-10
Meagher et al.
(1999)
4 Minutiae = 1 x 10-27
18 or more Minutiae = 1 x 10-97
Fully Rolled Print = 1 x 10-97
Table 2: Calculations made by Pankankti et al15
. Showing the likelihood of two prints having the
same number of matching Minutiae.
What is unknown to many is that friction ridge skin impressions were used as proof of a
person’s identity in China as early as 300 B.C., in Japan as early as A.D. 702, and in the
United States of America since 190216
.
Fingerprints are the only known non-invasive method of identification that is
accepted in Courts of Law of the United Kingdom 8
. There have been no reported cases
of identical fingerprints produced by two separate people, thus making them unique and

17
thus this is why they have been used as an excellent tool for identification for centuries.
This makes them an extremely important evidential tool in any criminal case.
Fingerprints like DNA have been used to identify the deceased, individuals with mental
instabilities and or amnesia sufferers; they can also place someone at a scene of a crime.
In particular, especially in the forensic context, large amounts of research has
gone into the developing of fingerprints, methods such as Gentian Violet (as well as
powders and superglue fuming; mentioned previously) all depend on the environment
that the fingerprint is discovered in17
. There have also been previous studies into the
detection and development of fingerprints on different substrate materials, ranging from
stereotypically smooth surfaces such as glass and metal to more porous objects like
papers and fabrics.
Unfortunately though when it comes to recovering viable prints from firearms
there is a very low success rate, this has been discussed in literature18–20
.
According to Barnum21
through February 1992 to August 1995, in the examination of
1000 firearms recovered at scenes 114 identifiable latent prints were developed on 93
firearms. That is a success rate of approximately one in ten. It should also be noted that
the identifiable print may have not been left by an offender, some of the recovered
prints subsequently belonged to persons involved with the handling of the firearm.
With this information there is strength behind the argument that ‘make safe’ procedures
may contaminate evidence and leave evidence from non-suspects in a case as well.

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2.4 Anatomy of the Fingerprint
2.4.1 Anatomy of the Skin
Now the initial question is, ‘What is a fingerprint?’ According to the Scientific Working
Group on Friction Ridge Analysis, Study and Technology22
a fingerprint can be defined
as:
‘An impression of the friction ridges of all or any part of the finger’
To really fully understand what a fingerprint is one needs to look at the anatomy of skin,
this is also paramount for the underline knowledge of how to examine them in a
forensic context.
The skin is an organ which is composed of three separate anatomical layers: the
epidermis, the dermis and the hypodermis23,24
, the skin acts as a protective barrier
against external harm and is also paramount for the temperature regulation of the body.
It also aids in sensation, secretion, immunity, synthesis of Vitamin D25
and finally acts
as a reservoir for the blood26,27
, though primarily most of features noted above are all
regulated or found within the outer layer, the epidermis.
The dermis supports the epidermis; it achieves this though layers of connective
tissue. The dermis primarily is constructed of cells, fibres, blood vessels and gelatinous
material. The other role of the dermis apart from support is participating in sensory
reception and temperature regulation.
Finally the hypodermis lies underneath the dermis and contains adipose (fat) tissues
which matches the contour of the body and acts primarily as an energy reserve for the
body.
The epidermis is made up of layered tissues that are renewed through a constant
process of cell replacement as the oldest cells die and are shed from the body. New cells

19
are generated in the lower (basal) layer and then migrate to the surface and during this
migration they undergo changes in their chemical composition25
. The epidermis is
comprised of several different types of cells: Keratinocytes, Langerhans, Melanocytes
and Merkel Cells. The cells lost at the surface and undergo migration and chemical
changes from the basal layer of the epidermis are the Keratinocytes.
Keratinocytes make up approximately ninety to ninety-five percent of the
epidermal layer23,25
and although these cells undergo chemical changes they are easily
distinguished by the presence of keratin filaments. Keratin is a protein which is
organised into bundles (or filaments) that extend throughout the cell and provide
structural support due to the durability of the protein. The keratin in the cells allows the
skin to undergo physical stress without the skin breaking. There are approximately 20
varieties of keratin, designated K1 through to K20. Though the keratinocytes found on
the friction ridges of fingerprints express Keratin cells which are not found anywhere
else on the body, specifically, K9, K6 and K16, this is attributed to larger amounts of
mechanical stress on friction ridge skin28
.

20
2.4.2 Friction Ridges
Primarily when focussing on fingerprints one is looking at the outermost layer of the
skin, the epidermis and also the friction ridges associated with them. A friction ridge is
a portion of the epidermis which is raised and aids with the placing of fingerprints.
Friction ridges persist on the body and are not eroded or abraded through mechanical,
loads or stress because of the physical attachments through the skin and the regulation
of keratinocyte production and differentiation, but although the ridges are persistent
they can age. Dr. Barbara Gilchrest defines this as
“an irreversible process which begins or accelerates at maturity and results in an
increasing number and/or range of deviations from the ideal state and/or decreasing
rate of return to the ideal state.”29
As the friction ridges on the skin age, the arrangement on the skin does not change but
they generally tend to flatten, making them appear less sharp and due to age, the dermis
loses elasticity causing the skin to become flaccid and wrinkle30,31
.
Primarily the pattern formed by friction ridges is based on some interrelated
factors32–35
:
 Shape and size of the volar pads, it was hypothesised by Penrose and O’Hara36
that the ridges follow the lines of curvature of the skin, Mathematical research
conducted by Smith37
confirmed this.

Bone morphology38
One factor that can change the friction ridge pattern of a fingerprint is through
the process of wound healing; the friction ridges persist through the lifetime of the
subject and generally remain unchanged unless there is a dramatic change in the
morphology of the keratinocytes. Injury causes the basal keratinocytes to change their

21
structure and physiology to repair the wound caused by the injury, the scar tissue
formed during the repairing process is a new and unique feature to the friction ridge
skin, the scar though can actually aid in the identification of an individual but this will
be discussed later. To rely upon the friction ridge skin as a means to identify people, it
is necessary to understand why the impressions of the friction ridge skin can be used
and what the physical limitations of the friction ridge skin are. If the variation in
appearance between two impressions of the friction ridge skin goes beyond the physical
limitations of the skin, the impressions cannot be from the same source.
A fingerprint is a negative image of the friction ridge pattern in the epidermis of
the skin, but just the ridges alone do not make the pattern, a composition of human
perspiration allow oily mark to be left. There are 3 major glands responsible for the
secretion of “sweat”, the eccrine, apocrine and sebaceous glands. The eccrine glands are
usually found throughout the body, but the highest densities are found in the palms and
soles. The sebaceous glands are typically localized to regions containing hair follicles,
as well as the face and scalp. The apocrine glands are found primarily in the axillary
regions (e.g., armpits and genital areas). However, in most instances, only the eccrine
and sebaceous glands contribute significantly to the latent print deposit. These glands
can be classified as tubular glands whose ducts open at the skin surface39
. Although the
composition of sweat is approximately 99% water40
studies have shown that a
considerable variety of chemical compounds are present. A recent study found
approximately 346 compounds (303 of which were positively identified) present in
surface skin residues41,42
).
Friction ridge skin has unique features that persist from before birth until
decomposition after death. Upon contact with a surface, the unique features of friction

22
ridge skin may leave an impression of corresponding unique details. Two impressions
can be analysed, compared, and evaluated, and if sufficient quality and quantity of detail
is present (or lacking) in a corresponding area of both impressions, a competent
examiner can effect an individualization or exclusion (identify or exclude an
individual). The analysis, comparison, evaluation, and verification methodology,
combined with the philosophy of quantitative–qualitative examinations, provide the
framework for practical application of the friction ridge examination discipline. But at
the heart of the discipline is the fundamental principle that allows for conclusive
determinations: the source of the impression, friction ridge skin, is unique and
persistent.
Empirical data collected in the medical and forensic communities continues to
validate the premises of uniqueness and persistence. One hundred years of observations
and statistical studies have provided critical supporting documentation of these
premises. Detailed explanations of the reasons behind uniqueness and persistence are
found in specific references that address very small facets of the underlying biology of
friction ridge skin.

23
2.5 Problems Associated with Latent Print Recovery on Firearms
2.5.1 Life of Latent Prints
There is no way of knowing when a fingerprint was laid upon an object, as discussed
before in optimal conditions fingerprints can survive on surfaces for periods of years,
the only way of having an approximate timeframe is if there was a witness to the event.
Professor Andre Moenssens, stated at the 57th
Annual Conference of the
International Association for Identification,
“I would simply say that I cannot tell with any degree of precision because there is no
known way to determine positively, or even closely approximate by opinion testimony,
the length of time a latent has been on an object. You can sometimes establish the length
of time a print has been on an object circumstantially, but not scientifically”43
.
In light of this Charles Midkiff examined results of experimentation done by others and
in his findings he states that;
“From studies and cases examined, it is apparent that wide variations exist in the
ability of a latent print to survive even under rather harsh conditions. Development of a
latent print at a crime scene is no guarantee of its having been recently placed. In
addition, the studies suggest that no reliable indication of a print’s freshness can be
obtained from its rate of development or appearance after it is developed. Speculation
or court testimony concerning the time when a latent print was placed may be
hazardous to the examiners reputation”44
.

24
2.5.2 Environmental Conditions
Primarily factors such as the air humidity and air temperature will affect the
survivability of latent prints and their subsequent development. For example air currents
will cause evaporation of the water component of the perspiration as well as a high air
temperature. High humidity can cause condensation to form which has the potential to
wash the print away43,45
.
Not only atmospheric conditions but factors that occur in the interim period
between the deposition of the print and the recovery of the firearm. Placing firearms in
holsters, waistbands, between car seats and under mattress can damage fingerprint
evidence, this also goes for weapons disposed of at speed e.g. thrown from vehicles or
into water sources.
A final factor which can act as a double edged sword is if there is any damage to
the friction ridge skin, permanent damage that leaves scar tissue tend to result in poor
fingerprints but are also advantageous of the uniqueness of scar tissue but temporary
damage generally poor latent fingerprints.

25
2.5.3 Processing Problems
Due to the varying conditions of metal surfaces on firearms and the relative smoothness
of that metal (semi-automatic, self-loading pistols tend to have more smooth surfaces
than revolvers), processing of firearms can prevent a problem. In addition the popular
trend towards the manufacture and purchase of polymer based firearms has the
disadvantageous fact that polymers generally have textured surfaces making them not
conducive to the retention of latent prints.
Prints may also become smudged and/or superimposed because of the way the
firearm is handled and/or the surface is dirty, oily or greasy. Usually the firearms
examiner must touch the same areas of the firearm during the ‘make safe’ procedure
that a potential suspect may have touched, one main combatant to this is wearing
appropriate PPE, such as latex or nitrile gloves but there is the risk of the destruction of
prints46
.
The final problem comes with the finishes that are applied to the metal surfaces
of firearms. One example being the rust preventative Parkerised finish found generally
on military firearms, it is notorious for poor latent print development. Firearms with
chrome, or stainless steel finishes provide better results21
.
A common finish known as a ‘blue’ finish, it is a rust-preventative coating, since
perspiration is approximately 98.5-99.5% water, bluing may retard latent print recovery.
Although Cantu et. al. Conducted an experiment following the case of a firearm which
had been ‘overblued’, with the use of acidified hydrogen peroxide latent sebaceous
prints were able to be developed47
.
In this work, a formula used by firearm and tool mark examiners to clean lead residue
from bullets was also found to remove gun blue coating from metal cartridge cases. The

26
mixture of acetic acid and hydrogen peroxide oxidised the coating into a solution, it was
also found to etch the metal of the casing that had no sebaceous residues and thus the
subsequent treating for latent prints was enhanced.

27
2.6 Materials used in Firearm Manufacture
2.6.1 Metals
2.6.1.1 Steel
The traditional material used in firearms construction is a high carbon, heat treated steel,
and this is found usually in semi-automatic pistols, revolvers and rifles. It is used so
commonly due to the fact that it is very durable and can be manipulated in many ways;
it can be forged or machined into shape. Due to its strength it also has a relatively thin
structural cross section compared to other materials, and this usually plays a role when
creating ergonomic grips.
Major structures such as slides and frames can be made with castings while for
smaller parts, metal-injection-moulding (MIM) process is utilised. This process can
accurately reproduce parts that require little to no finish machining. Most
manufacturers, including those who advertise forged construction tend to utilise the
MIM process to control costs48,49
.
MIM can create parts with very little shrinkage and high dimensional accuracy and
sometimes can rival machined forgings on reliability.
The weight of steel aids in control and aiming and also steel framed firearms or
firearms with lots of steel will recoil less than lighter materials due to mass times
velocity = energy.
Steel is also easily finished with blueing, Nickel or Chrome plating and Manganese
Phosphate (Parkerising).
The drawback of steel is the weight, the need for constant lubrication and corrosion
protection49
.

28
2.6.1.2 Aluminium
Before World War II aluminium, though one of the most prevalent metals was
expensive to refine from raw ore and there was a traditional distaste for its use in
firearms. The use of aluminium alloys was the industry’s first major post-war
development for pistols, particularly for constant carry purposes. Colt introduced the
Lightweight Commander in 1949, a slightly shortened and 30% lighter version of the
Government Model, as an offshoot of the General Officer’s Pistol program of the era.
It can be reliably stated that aluminium framed arms are not as durable as a steel
one of equivalent design and cross section. Aluminium does not have the tensile
strength of steel. The aluminium alloy must be carefully chosen and as much as 50%
thicker in cross section, compared to an equivalent steel part. The cross section of a
material becomes important to the shooter, not only because of weight, but also due to
ergonomic issues, such as balance and grip width. The most prevalent surface finish
used on aluminium has been some form of hard-anodizing process. It offers greater
corrosion and wear resistance and does not increase weight. Drawbacks include greater
felt recoil. Some aluminium alloys cannot be welded, including the “Coltalloy” used in
the Commander. Repairs are generally not possible if fatigue cracks occur, although this
also means that the expected life of the arm has been exceeded49
.

29
2.6.2 Woods
While walnut is the favoured gunstock wood, many other woods are used, including
maple, myrtle, birch, and mesquite. In making stocks from solid wood, one must take
into account the natural properties and variability of woods. The grain of the wood
determines the strength, and the grain should flow through the wrist of the stock and out
the toe; having the grain perpendicular to these areas weakens the stock considerably50
.
In addition to the type of wood, how it is treated can have a significant impact
on its properties. Wood for gunstocks should be slowly dried, to prevent grain collapse
and splitting, and also to preserve the natural colour of the wood; custom stock-makers
will buy blanks that have been dried two to three years and then dry it for several
additional years before working it into a stock. Careful selection can yield distinctive
and attractive features, such as crotch figure, feathering, fiddleback, and burl, which can
significantly add to the desirability of a stock. Blanks for one piece stocks are more
expensive than blanks for two piece stocks, due to the greater difficulty in finding the
longer blanks with desirable figure. Two piece stocks are ideally made from a single
blank, so that the wood in both parts shows similar colour and figure51
.
Laminated wood consists of two or more layers of wood, impregnated with glue
and attached permanently to each other. The combination of the two pieces of wood, if
laid out correctly, results in the separate pieces moderating the effects of changes in
temperature and humidity. Modern laminates consist of 1.6 mm thick sheets of wood,
usually birch, which are impregnated with epoxy, laid with alternating grain directions,
and cured at high temperatures and pressures. The resulting composite material is far
stronger than the original wood, free from internal defects, and nearly immune to
warping from heat or moisture. Typically, each layer of the laminate is dyed before

30
laminating, often with alternating colours, which provides a pattern similar to wood
grain when cut into shape, and with bright, contrasting colours, the results can be very
striking. The disadvantage of laminate stocks is density, with laminates weighing about
110 to 140g more than walnut for a typical stock52
.

31
2.6.3 Polymers
The use of plastics in pistol construction was limited to non-structural items, such as
grips and recoil spring guides, until the German firm of Heckler and Koch introduced
the polymer framed Model VP-70 in the mid-1970s. While Steyr-Daimler-Puch of
Austria made extensive use of polymer for the AUG assault rifle, the real revolution
began with Gaston Glock’s seminal G17 of 1983. Not only did Glock use the material
for the frame, he used it for a number of the smaller parts, as well. Anti-gun lobbyists of
the time attempted to argue that these plastic guns were not metal detectable in security
areas. This was an outright lie, as all plastic pistols have a large steel component in
other functioning parts. Plastic components were adopted for multiple reasons. Most
obvious, is weight savings.
Another is manufacturing economy. While the precision injection moulds are expensive
to produce, once done the moulded parts are quickly and cheaply made. This is no small
matter for any company concerned with cost savings on metal cutting equipment, and
profit per unit sold at normal retail levels.
While over-pressure cartridges can damage steel or aluminium framed pistols,
there are many more reports of polymer-framed pistols suffering explosive destruction,
due to the material itself failing. These instances are relatively rare, considering the
sheer number of polymer pistols sold, but the numbers are still significant. Arms
manufacturers must take this into their economic calculus when considering legal costs
against production savings49,53,54
.

32
2.7 Places where Fingerprints can be found on a Firearm and Make Safe
Procedures
Stated before, fingerprints are deposited by the friction ridge skin of the individual. In
regards to where fingerprints are left on firearms there are many factors influencing
where the initial fingerprint is deposited. These factors included, how the firearm is
handled, and why it is handled, for example someone holding a firearm with intent to
use t will place their hands in a different position to someone who is maybe passing it to
another person or casually picking it up.
Also dependant on the type of the firearm there are potential for prints to be found in
places that would not appear on other firearms.
2.7.2 Pistols
With pistols, when one holds the firearm in a manner as if they were going to use it,
generally that person at some point must place their hand around the grip which may or
may not be ergonomic in design, this will cause deposition of prints, this is the case for
persons who hold the firearm one handed or two handed.
Figure 1: Glock 17 in a one handed grip

33
Figure 2: Glock 17 in a two handed Grip
In the scenario that someone is picking up a completely unloaded firearm,
loading it and getting ready to take a shot they will normally follow this protocol. First
the firearm will be picked up via the grip, then with the free hand the magazine will be
picked up and inserted into the firearm, (usually through the bottom of the grip) from
here the external safety (if one is present) will be disengage and with their hand the user
will motion the slide rearwards to cycle a round into the chamber. Also if the external
hammer (if one is present) has not been cocked this will happen and then the finger will
be placed on the trigger. In this short routine there are at least 6 places where
fingerprints may have been deposited.

34
Figure 3: Magazine being released on a 1911, note the left thumb is covering the release button
Figure 4: 1911 in a one handed grip with the hammer locked rearward due to mechanical means
In the scenario of a bystander picking up the weapon they will most likely utilise
the grip and possibly finger the trigger, and also in some cases may touch places such as
the magazine release catch.

35
Finally if someone is passing another person a fire arm, again to pick up the
firearm the grip may be used but most people would grip around the slides
normally depositing fingerprints on the underside of the slide.
2.7.3 Revolvers
With Revolvers, prints can be deposited on grip, or barrel if the firearm is being
passed to another person potentially there could be prints on the barrel.
Due to the construction of the firearm being different from that of a self-loading pistol
there is no slide or external magazine, instead the revolver has a revolving cylinder
where the ammunition is stored, but similar to self-loading pistol there is a button that
allows access to the cylinder.
Figure 5: Thumb is covering the Cylinder Release Catch on this Smith & Wesson .357
The cylinder must be rotated manually thus leaving a potential surface for
fingerprints, also since the ammunition is loaded into the cylinder and after firing is not
ejected with the two surfaces of the rear face of the cylinder and the brass of the
cartridge leaves another surface for fingerprint deposition.

36
Figure 6: Cylinder utilising a hinge, being opened, note positioning of fingers on the cylinder
With revolvers, they commonly have an external hammer and sometimes an
external safety too; again these are surfaces for which fingerprints can be deposited. It
must be noted as well that pistols, but more commonly revolvers can actuate with the
hammer pulled to the rear (Single Action) or with a heavy pull of the trigger (Double
Action) so if no fingerprints can be found on the hammer the trigger is a logical place to
look also.
Figure 7: Exposed hammer being locked in the rear position, cocking the firearm

37
Antique Revolvers, or modern reproduction of antiques, may not have a button
to access the cylinder they may have a loading gate which needs to be opened on a
hinge, the hammer pulled half way to the rear and then the cylinder rotated manually
allowing ammunition to be loaded, while some may involve a ‘shoe’ lever allowing the
revolver to be ‘broken’ in half on the axis of a hinge.
2.7.4 Rifles
Like with other firearms areas such as the trigger and grip will be likely places for
fingerprint recovery but also as it is a ‘long-arm’ the fore grip is a place for deposition
and recovery, also note that dependant on the type of rifle will depend on whether it has
a rifle grip or a pistol grip.
With bolt action rifles the rounds can be loaded into an external box magazine
which is then inserted into the firearm, single rounds can be placed into the chamber or
in some models, the rounds are loaded trough the top of the open chamber into a fixed
magazine, this can be aided with the use of a stripper clip, these are disposable and can
sometimes be recovered at the scene.
To cycle rounds in this particular type of rifle, the bolt is gripped with the whole of one
hand, and normally lifted upwards about 45o
or 90o
degrees and then moved rearward
where the round is extracted and ejected, the bolt is then pushed forward and returned to
its original position. Safety catches and magazine releases are also prime places for
fingerprint deposition.

38
Figure 8: Bolt of rifle being gripped by operator
Semi-Automatic rifles are loaded via an external magazine or with an internal
magazine, like the bolt action rifle, there is also a bolt to cycle ammunition into the
chamber, and this generally is known as a straight pull bolt because it is pull rearward
towards to stock or rear of the rifle. Like the bolt action, trigger, grip, bolt and Magazine
Not as common rifles, such as pump-action rifles utilise a rearward moving fore-grip to
cycle rounds.
Muzzle loading rifles generally need to have the butt plate placed on the ground
and one hand is used to support the barrel around the mid-point. The free hand is used
to load the shot so there is a possibility of fingerprints being left on and near the muzzle.
Assault rifles and Submachine guns, though not commonly encountered in
Firearm related crimes in the United Kingdom, are still a worry and potentially can be
smuggled in through port authorities and customs.
Assault rifles and Submachine guns are all loaded through the use of external
box magazines, thus leading to fingerprint deposition as well as pistol grips. Like the
semi-automatic rifle the round first round in the magazine must be inserted into the

39
chamber, this is done by utilising straight bolt with a cocking, like the semi-automatic
rifle, to cock the weapon it is a case of grasping the bolt, pulling it to the rear and
allowing it to move forward to collect the round from the magazine and deposit it in the
chamber.
Figure 9: Magazine from AK-47 Variant being released using the magazine release lever.
Figure 10: Charging/Cocking Handle being pulled rearward to action the rifle

40
Figure 11: Common method of holding the firearm during operation
Figure 12: M16 Magazine being released by Magazine release button

41
Figure 13: 'T-bar' Cocking handle of the M16
2.7.5 Shotguns
Shotguns, like rifles are long arms, and thus have many of the same places that rifles
have to deposit prints, one difference comes in the way they are loaded. Shotguns
generally come into three categories, Break Action, Pump Action and Semi-Automatic.
Break action are loaded by moving a lever to the right causing the action to break on a
hinge, exposing the chambers, the lever is a surface for fingerprint deposition, On semi-
automatic the loading gate and the cocking handle also act as surfaces and the moving
foregrip on pump action shotguns as well as the loading gate.

42
Figure 14: Pump Action Shotgun, with Pump slide to the rear leaving the chamber open
Muzzle loading shotguns are not as common but can be found occasionally and
are loaded in a similar fashion to muzzle loaded rifles and thus would have fingerprints
found in similar places.

43
2.7.6 Machine Guns
Machine guns are generally used as military support weapons that are very rare rarely
encountered in crime, and are sub divided into two categories; Light and Heavy, based
primarily on the calibre it is chambered for.
Now machine guns are either fed from box magazines, inserted vertically into
the top of the body like the BREN gun or from underneath like certain Minimi variants.
Or the machine gun may be fed by a belt, either made of cloth to be reused or from
disintegrating links.
First of all, when looking at places of fingerprint deposits, since most machine guns
feature a pistol grip that will be the primary area to search along with associated safety
catches and the trigger.
Most Machine guns will feature a foregrip but can also utilise a bipod or tripod
for better stability so as well as searching the foregrip, the stabilisation platforms can be
investigated.
If, for example the dusting is being carried out on scene and the stabilisation platform is
engaged, then occasionally the stock, especially on models from Russia and associated
countries will feature a vacancy where the operator may hold on to, to allow for a
tighter shooting position.
The way a belt fed machine gun is loaded allows for multiple surfaces for
fingerprint deposition. Initially there is the top cover release button or catch, the the top
cover which will pivot on a hinge away from the gunner.
Next is the trap, where the belt is engaged into, so the trap should be investigated all
over.

44
Finally the bolt needs to be engaged, like semi-automatic rifles, submachine guns,
assault rifles and semi-automatic shotguns, the machine gun will utilise a straight bolt
with a cocking handle.
One thing that must be noted, as previously mentioned, magazines and cylinders
have been indicated as potential places for fingerprint deposition, with belt fed machine
guns, the belt and links can also be investigated.

45
2.8 Possible Encountered Substrates
As mentioned previously in this report, there are generally set methods for the
development and recovery of fingerprints and these methods are designed based on the
substrate in which the fingerprint has been deposited, in Chapter 2.6, the materials used
in the manufacture of firearms was discussed, the main materials mentioned were
polymers, woods and metals, it also must be noted that rubbers can be present in grips
and foregrips though that is not an extensive list.

46
Type of Material Material Details Location on Firearm
Metals
Steel
Plain/Stainless
Generally Interior
components,
occasionally seen on
the exterior of the
firearm, Magazines
Blued
Exterior components
such as slide,
hammers, body of the
firearm and various
releases and catches
Chrome Plated
Nickel
Plated/Finished
Parkerised
Engraved
Aluminium
Plain/Stainless
Generally Interior
components,
occasionally seen on
the exterior of the
firearm
Blued Exterior components
such as slide,
hammers, body of the
firearm and various
releases and catches
Chrome Plated
Nickel
Plated/Finished
Engraved
Wood -
Untreated
Stocks, Heels, Grips,
Foregrips
Varnished
Sanded
Feathered
Engraved
Polymers Plastics
Mouldings
Main Body, Grips,
Stocks, various
catches and releases.
Stellated
Stippled
Treated
Rubbers High Density
Porous Foregrips Stock Pads,
Ergonomic GripsMoulded
Miscellaneous Ivory - Grips, Sights
Enamels - Grips, Sights
Table 3: Table listing some of the components and materials found in firearms manufacture
Champod et al.55
suggest methods that distinguish whether a fingerprint is wet or
dry as shown below.
However CAST have developed a handbook or those working with fingerprints that
provides a flowchart suggesting the best routes to take based on the substrate material as
well as considering the condition of the fingerprint.

47
This method provides a more detailed approach for the investigator and allows also one
to look at the specific reagents needed to develop the fingerprints.
In this chapter the most appropriate methods for each substrate will be identified
and discussed.
With all development techniques the first and foremost is the use of oblique lighting and
different wavelength lights to first visualise if any prints are there, if located
photography of the print must occur.
After this the actual development of prints can occur, the use of ultraviolet or
high wavelength lights to promote fluorescence is normally employed as it can be done
in situ and is non-destructive to the print but can require specialised equipment and
films, if photography is required. From this points the techniques differ dependant on
the substrate materials, we will be discussing the methods in regards to the substrate
material, not where that material might be found on a firearm.

48
Figure 15: Champod's Suggested method of Fingerprint Development

49
2.8.1 Smooth Non-Porous Materials
Materials under this classification would represent surfaces such as glass, paints,
varnishes, hard plastic mouldings and certain treated metals. The seemingly obvious
first step, (after visual examination and photography) would be the use of powders to
develop any latent prints present and as shown in the figure below that is one particular
route the investigator may take. If, however the evidence is contaminated with a grease
than techniques such as powdering and and small particle reagents may fall foul and
coat the entire evidence in powder rather than the latent print, if this is the case it is
suggested to to move from physical onto chemical development, here Solvent Black 3
and Gentian Violet are recommended, Cyanoacrylate fuming may be an option if the
article is dry.
Figure 16: CAST's Recommendation for Fingerprint Development on Smooth Non-Porous
Materials

50
2.8.2 Rough Non-Porous Materials
Rough surfaces are generally less productive in generating viable prints, powders, due
to the uneven surface, are generally the least effective development as the powder
settles in the roughs and furrows of the of the substrate material.
Latent fingerprints on these surfaces can be easily damaged if mishandled or
mispackaged or not transported with care, the most effective method for the
development of prints on these surfaces s superglue fuming.
Figure 17: CAST's Recommendation for Fingerprint Development on Rough Non-Porous Material

51
2.8.3 Vinyl, Rubber and Leather
Fingerprints are notoriously hard to develop on these surfaces due to normally waxes or
plasticisers added to the material to increase durability and resistance to weather.
These waxes and plasticisers are usually fatty materials which have the potential
to be similar to the chemical composition of the fats and amino acids found in the sweat
component of fingerprints thus making development of the prints inherently difficult.
Due to the unreliability of recovering viable print marks there is little information
available on these substrates2
.
Figure 18: CAST's Recommendation for Fingerprint Development on Vinyl’s, Rubbers, and
Leathers

52
2.8.4 Metals
Due to the inherently rough nature of metals, many are treated or lacquered not only to
create a smooth finish and too add corrosion resistant and weatherproofing properties to
the metal.
If the metal has been treated that it can be treated as a smooth non porous object and the
chart shown in figure…… would be more appropriate. If the metal however is ‘raw’ i.e.
untreated the chart below would be more appropriate to use.
Due to the rough nature of the material prints can be damaged or destroyed fairly
easily so care must be taken when developing, packaging or transporting any materials
that need to be examined.
Figure 19: CAST's Recommendation for Fingerprint Development on Metals

53
2.8.5 Woods
Due to the inherently rough nature of woods, many are treated or lacquered not only to
create a smooth finish and too add corrosion resistant and weatherproofing properties to
the metal.
If the metal has been treated that it can be treated as a smooth no porous object and the
chart shown in figure 16 would be more appropriate. If the metal however is ‘raw’ i.e.
untreated the chart below would be more appropriate to use.
Due to the rough nature of the material prints can be damaged or destroyed fairly
easily so care must be taken when developing, packaging or transporting any materials
that need to be examined.
Figure 20: CAST's Recommendation for Fingerprint Development on Woods

54
2.8.6 Fabrics
There is no proven process for the development of latent fingerprints on fabrics, the
chart provided below, adapted from the models produced by CAST suggests using a
mix of models.
The radioactive Sulphur Dioxide Process may offer the possibility of fingerprint
development, but is generally unsuccessful. The chances of developing viable latent
prints is severely reduced of the fabric is dirty or if it has a nap (raised fibres on the
surface on the fabric). If fabric articles are recovered and it is believed that there is a
possibility of recovering viable prints then the article must be subjected to the minimum
of handling, folding and creasing as well as being properly packaged and transported
with care.
Figure 21: CAST's Recommendation for Fingerprint Development on Fabrics

55
2.9 Fingerprint Development Methods and Reagents
2.9.1 Visual Examination
The visual examination of fingerprints can be conducted on nearly any clean, relatively
flat surface. It tends to fall short on porous materials. It is extremely sensitive also
allows for the visualisation and documentation of older prints. The visual examination
can then be further assisted with the use of a high wattage lamp the technique of oblique
lighting can be used to help illuminate any latent prints which may be present;
unfortunately it is a technique that requires an experienced operator to initially locate
the prints in question.
2.9.2 Fluorescence Examination
Fluorescence is the property that some chemicals possess of being able to absorb light
of a specific wavelength and then emit some of the absorbed energy from the incoming
emission at a different wavelength resulting in a colour change.
Generally radiation in the ultraviolet, blue and/or green parts of the
electromagnetic spectrum are utilised to excite fluorescence which may result in the
emission of energy in the yellow to infra-red parts of the electromagnetic spectrum.
Most of the illuminating energy is not absorbed by the sample, but scattered or reflected
from the surface being examined. Filters which transmit the fluorescence but not the
illuminating light are placed in front of the eye of the recording device (camera) to
enable the fluorescence to be visualised and recorded.
A filter must be chosen which will transmit most of the fluorescence but not a
significant amount of incident energy, so that adequate protection for the investigators
eyes is provided. This usually indicates that transmission of the filter over the
wavelength range of incidence should be less than 10-4
nm2
.

56
Application Excitation Filter (nm) Viewing Filter (nm)
Examination of all surfaces.
Background Fluorescence may
obscure some fingerprints
Blue
352-509
385-509
354-519
385-519
400-519
Yellow/Orange
510
or
515
Orange 529
Reduces Background
Fluorescence
Blue/Green 468-526 Orange 529
Reduces Background
Fluorescence Further
Green 473-548 Orange 549
Detects some fingerprints on
polythene and possibly other
surfaces
Green 491-548 Orange 549
Fingerprints in Dark Materials
Violet/Blue
350-469
385-469
Yellow 476
UV 280-413 Yellow 415
Table 4: Application of Wavelengths to cause Fluorescence2
The illumination required to cause excitation and thus fluorescence varies from
chemical to chemical and due to this the emitted energy will also vary from wavelength
to wavelength.
The Fluorescence may be initiated from an external energy such as a black light
or the fingerprint may be dusted in powder, or developed in a chemical which has
fluorescent properties.

57
Application Excitation Filter (nm)
Viewing Filter
(nm)
Absorbing Treatments, e.g.
Ninhydrin
Violet/Blue
350-469
385-469
400-469
Yellow 476
Acid Yellow 7 Blue
352-509
385-509
354-519
385-519
400-519
Yellow
510
or
515
Orange 529
DFO
Green
Green
Green/Yellow
473-548
491-548
503-591
Orange
Orange
Red
549
549
593
Gentian Violet Green/Yellow 503-591 Red 593
Ninhydrin toned with Zinc Blue/Green 468-526 Orange 529
Superglue with Basic 40 Violet/Blue
350-469
385-469
400-469
Yellow 476
Superglue with Red 14 Green 473-548 Orange 549
Table 5: Enhancing Developed Fingerprints2
2.9.3 Gentian Violet
Gentian Violet is a dye which stains fatty constituents of sebaceous sweat producing an
intense purple image. It is very effective for the the development of latent fingerprint
located on adhesive coated surfaces such as fingerprint lifting tape. It will also develop
prints contaminated with grease. The reagent is easy to use but phenol is toxic when
swallowed or absorbed through the skin as is basic violet 3. Therefore Gentian Violet
should not be used in large volumes.
2.9.4 Ninhydrin/DFO
Ninhydrin is a chemical which reacts with primary and secondary amines and induces a
colour change, the end result being a dark purple colour.
As the eccrine component of a latent print contains amino acids, this reaction can be
exploited as a mean of developing prints on porous surfaces.

58
The use of Ninhydrin as a developing reagent was first proposed by Oden and Von
Hofsten56
in 1954.
Figure 22: The Reaction of Ninhydrin in the presence of an Amine
Eccrine glands secret a range of amino acids that may ultimately present
themselves in the print24,57
. Ninhydrin is a non-specific reagent and will react with all
amino acids in a similar way producing a repeatable end result.
Amino Acids are stable compound that have an affinity for cellulose and do not migrate
through dry paper substrates means that very old prints may be developed. DFO (1, 8-
diazafluron-9-one) is an analogue of Ninhydrin.

59
Figure 23: The full Ninhydrin reaction, taken from Champod
DFO, has an advantage over ninhydrin, firstly it doesn’t need a secondary
treatment and when developed room temperature marks show a strong luminescence but
according to Pounds et al58
, heat is required for a period of less than thirty minutes to
optimise visualisation.
Figure 24: DFO reaction, taken from Champod

60
2.9.5 Physical Developer
Physical Developer is a silver-based aqueous reagent which reacts with the components
of sebaceous sweat to form a silver-grey deposit of Iron and Silver atoms. The article of
evidence is placed into a solution of Physical Developer and left to allow the redox
(reduction/oxidation reaction) to occur. Development can take anywhere from ten
minutes to one hour. This reagent is commonly used after Ninhydrin and DFO
treatments if they fail to reveal any useful marks and/or ridge details. This treatment can
be repeated to increase the amount of deposited material on the mark to allow for a
greater contrast of the mark against the substrate but the investigator must be wary that
any overdevelopment of the mark cannot be reversed55
.
Usually this treatment is used on paper but can be used on raw (untreated)
woods2
.
This method has some major drawbacks as it is very delicate and time consuming to
prepare as well as develop. The solution is relatively expensive to produce and has an
extremely short shelf life (less than 2 weeks) it is also destructive as it permanently
stains the substrate material. At the time of this writing there is currently research being
conducted within the U.S. Secret Service to produce a physical developer based on
copper, rather than silver, this would reduce overall costs to manufacture the reagent
and would also render any developed marks luminescent59
.

61
2.9.6 Powders
Powdering is the traditional method for visualising fingerprints at crime scenes, the
process is a physical one where the powder is brushed or dusted over the suspected print
and the powder itself is retained by any humid, sticky or greasy components of the
latent print. The application of the powder is inexpensive and requires minimal training
to do so efficiently; any prints which are developed can be lifted using adhesive tapes or
gel lifters.
Though due to its ease powdering does have some weaknesses, the main one
being that only fresh prints will be developed, as the print ages more of the sweat
component of the print will evaporate, leaving less area of the print for the powders to
adhere, also if the material is porous the print may be absorbed slightly into the
substrate thus slightly concealing the full features of the print.
Also choosing the appropriate powder type and brush type is something that comes with
experience so the less experienced examiner may not achieve the optimum results
depending on their choice of powders and brushes.
Regular powders generally consist of a resinous polymer for adhesion and a
colorant to provide contrast against the substrate3,24
. The adhesive is adhered by the
moisture are oily components of the sweat by the pressure deficit system60
, while the
colorant gets adsorbed on the adhesive. With this the ridge pattern is visualised,
common adhesives include; starch kaolin, rosin and silica gel.
One of the most common fingerprint powders, recommended by Thomas60
is an
‘Aluminium Powder’ also known as Argentoratum. James et al61
in their own research
confirmed Thomas’ conclusions.

62
James et al, also created fine flake powders combined with stearic acid in weight
rations ranging from 0-50%. These compositions were produced by laboratory scale
milling of aluminium, zinc, copper and iron powders.
The authors assessed the effectiveness of these formulations by comparing the results
with regular aluminium, black, and commercial dark powders. It was found that the
aluminium preformed extremely close to its optimum level while improvements could
be made to the two dark powders.
A good number of powder formulations contain natural or synthetic organic
derivatives that fluoresce or phosphoresce upon exposure to ultraviolet lights or laser
lights.
The main advantage of such compositions is that they allow for a greater contrast when
the print is located on a substrate which does not offer the best visualisation.
One notably disadvantage to powders is many of the metallic formulations have
now been phased out due to the toxic nature of heavy metals.
There have been studies62,63
both studies found that fingerprint powders did pose a
potential risk to health especially in enclosed unventilated areas such as on scenes rather
than ventilated fume cupboards in the labs.

63
2.9.7 Radioactive Sulphur Dioxide
Sulphur dioxide gas dissolves in the water that is present in latent fingerprints and there
may also be some reaction with the fatty constituents. After an exhibit has been exposed
to Radioactive Sulphur Dioxide, the presence of fingerprints may be detected and
recorded by autoradiography.
This method can be used on surfaces that fingerprints are hard to recover from and
reacts with the water content of the fingerprint, therefore it would work on eccrine
fingerprints however it involves expensive equipment and can provide health issues if
not carried out safely64
.
2.9.8 Solvent Black 3
Solvent Black 3, also known as Sudan black, is a dye which stains fatty components in
sebaceous sweat to produce a blue black image. It is known to be less sensitive than
other methods of print development, but it is particularly useful when treating surfaces
which have been contaminated with grease, foodstuffs and certain beverages, it can also
be used to further develop polycyanoacrylate but other methods are more efficient and
thus are recommended .
There are two main formulations of Solvent Black 3. An ethanolic formulation,
recommended for laboratory use only and one which is based on 1-methoxy-2-propanol
that is recommended for use during field work at crime scenes. The methoxypropanol
based formulation is flammable but only at temperatures of 48o
C and above.

64
2.9.9 Superglue
Cyanoacrylate esters, are colourless, monomeric liquids which are sold commercially as
rapid high strength adhesive glues (e.g. ‘Superglue’). When heated as the cyanoacrylate
evaporates it forms a vapour which reacts with certain eccrine and sebaceous
compounds in latent fingerprints.
The end result of this reaction is the vapour polymerising on the ridges of the latent
fingerprint to form a hard white polymer which is known as polycyanoacrylate.
Figure 25: Cyanoacrylate (Superglue) Reaction
Because of this fingerprints with a high ratio of sebaceous sweat are highly sensitive to
this technique, though the vapours also react with some eccrine components in the
deposit65
.
Numerous methods for this technique have been proposed and there are multiple
commercial units available in the market, though simple homemade units consisting of a
chamber, vacuum system and a heat source can readily be made in a cost effective
manner.
Commercial units have the advantage of more accurate heat control, greater possibility
for full hermetical seals and better vacuum systems for vapour circulation and removal.
When using this technique it is good practice to place a control fingerprint on a
glass slide, if possible to see whether the treatment is working.

65
Cyanoacrylate vapours are classified as an eye and respiratory tract irritant,
therefore exposure to the vapours should be minimised 66
. It has been indicated by
Mock67
, that excessive heating, to temperatures in the range of 220o
C and above may
form the toxic gas Hydrogen Cyanide. It has also been noted by Mock that
cyanoacrylate vapours have a flash point just over the 90o
C mark and thus could ignite
under certain circumstances. It has been reported as well, that polycyanoacrylate is
heated to above 205o
C that there is a possibility of the formation of Cyanide Gas 68
.
One variation of the cyanoacrylate fuming method proposed by Jian and Dao-
An69
. This method involves mixing a solution of cyanoacrylate ester is prepared my
mixing liquid cyanoacrylate glue with diethyl ether in either 1 : 1 or 1 : 2 proportions.
With this solution, a piece of regular filter paper is soaked and then allowed to dry for
several minutes. The paper is then placed lightly on top of the area believed to contain
the latent print, any prints in close proximity will be developed by the naturally emitted
vapours from the cyanoacrylate, the paper has to left in place anywhere between five
minutes and one hour. According to the authors of this paper (Jian and Dao-An) this
method has been used in 1000 cases since 1987 to the time of publication and good
results are reported on many substrates including plastics, metals and fabrics.
Polycyanoacrylate can be further developed with coloured or luminescent stains,
to ensure the integrity of the prints usually after the cyanoacrylate fuming method, it is
suggested they are left for a period of twenty four hours before any staining attempts.

66
2.10 Make Safe Procedures
As stated in the introduction a ‘make safe’ procedure is a series of actions preformed to
render a firearm at a scene safe to handle.
Now usually as far as research goes, many law enforcement, and military forces that use
these methods document them in their Standard Operating Procedures, which are
usually not distributed among the public.
In this chapter I will be looking briefly at make safe procedures from separate
forces and comparing them.
2.10.1 ASET Method
Upon talking with Dave Harris of ASET Group, based at the Defence Academy
of the United Kingdom, he instructed me in the process that they use and teach to
various other law enforcement groups.
The method utilised by this group is seven stage process;
1. Thorough Visual Assessment of the firearm.
2. Identify and choose a safe direction, being aware of what is in and behind the
area chosen.
3. Take control of the firearm.
4. Disengage the Hammer and Engage the Safety
5. Remove the Supply
6. Clear the Mechanism and carry out a BBC (Breech, Body, and Chamber)
Check.
7. Declare the weapon clear or loaded.
The first stage is a thorough visual check, it is recommended to find a single point
on the firearm and work clock wise, so for example if one was to start at the muzzle, the

67
examination should start with an oblique look at the barrel to determine size of barrel
(allows identification of full bore firearms or air weapons etc.), also if possible with
oblique lighting one should try to identify any rifling if they can, then moving around
the top of the slide the sights should be identified, plus if any hammer is present and the
current location it is in, this is also required for any catches, levers or buttons, though
they may be on the blindside and may need to be identified when the firearm is in
control of the examiner.
Any markings should be noted down on the slide, and on the grips. One should note is
there is a magazine present, and whether that magazine has any valves for pressurisation
(air weapons). Any accessories such as lanyard attachments, extended magazines,
muzzle breaks and flash suppressors should be noted during this examination.
Stage two, requires the examiner to identify a safe direction, inform everyone in
the area of that direction and also be aware of what may possibly be behind that
direction in case of a negligent discharge.
For example a concrete wall would be preferably to a drywall or glass window;
basically the direction should involve something that can absorb a bullet impact.
It should be noted that some forces have specific make bags, with aramid plates or cups
that can be aimed at.
Stage three is to take control of the firearm, wherever it may be, this means
making sure the examiner has a firm grip on the weapon and the muzzle is always
pointing in a safe direction while keeping their finger away from the trigger. As
mentioned in stage one, here the examiner may have to examine the blindside of the
weapon, this can be done either by controlling the weapon and rotating it laterally

68
around the Y axis, or the examiners moving their head to obtain the best line of sight
without deviating from the safe direction.
Stage four involves the ‘de-cocking’ of hammers and engaging any safety
catches, now this should only be done if the examiner is one hundred percent sure they
need to do this to be able to carry on with the make safe.
If they are unsure, it is recommended for them to leave it.
To lower the hammer, one must take their free hand and place their finger between the
hammer and the rear of the slide, they then pull the on the trigger and return their trigger
finger to a safe place, the hammer should fall and get stuck on the examiners finger,
then using the hand to grip the firearm, they place their thumb on the hammer and exert
rearward pressure, remove the trapped finger and then ease the hammer forward.
Stage five is to remove the supply, the Americans use the term, dumping the
mag. essentially the examiner is removing the ammunition source with care, and then
examining the magazine or ammunition to see if it is consistent with the firearm in
question.
Stage six, is to clear the mechanism, so this would mean grabbing the bolt or
slide and pulling it to the rear, now for weapons such as assault rifles and machine guns
where the springs used are high tension, the bolt will lock to the rear automatically and
stay in place. With weapons such as Self Loading Pistols the slide may, or may not lock
back so tension must be held at all times.
If a round of ammunition is ejected, the examiner is encouraged to say out loud that a
round has ejected, now with the bolt or slide held back a BBC check is conducted, these
differ from firearm to firearm as these components are located in different places, so to

69
weapon is kept in the safe direction and the body is move around to check to see if the
locations are clear.
The final stage is to declare the firearm clear, if the examiner is one hundred
percent sure that there is no ammunition in the firearm and that is cannot be discharged
in anyway, purposefully or negligently. If they are unsure in anyway then they declare
the weapon as loaded.

70
Chapter 3: METHODOLOGY AND METHODS
3.1 Methodology
The methodologies of developing latent fingerprints has been researched throughout the
years and can be split between the types of development or visualisation methods
required for the examiner at that particular scenario, again dependant on the
circumstances associated with the latent print such as age, location, substrate surface
and environmental conditions etc.
Regardless the methodologies of associated with latent fingerprints can be
divided into 3 broad areas; the methodology of using powders to visualise or develop
the print, the methodology of chemical methods to visualise or develop the print and
finally the methodology of successfully recovering the print after either means of
visualisation.
In regards to the use of powders, the standard methodology will usually utilise a
fine hair or fibre brush slightly immersed into the powder and then brush will either be
slightly agitated by rotating the handle around the Y axis to cause the powder to drift
onto the substrate and the latent print located on that surface. The alternative to this
method is once the powder is located on the brush fibres, the examiner will gently brush
in one direction over the print and repeat, causing a cumulative layer of powder to be
adhered to the print and thus developing it.
There are disadvantages with both methods, for example the brushing method
can easily cause the print to become damaged if the examiner brushes with the wrong
fibre brush or if they are too vigorous in their brushing. With the method that involves
non-contact it is very easy to supply the brush with too much powder and overdevelop
the print, granted there are techniques available to try and remove any excess the

71
powder but there is an inherent risk associated with these methods, the risk being that
may not remove excess powder but just relocate it on the print or actually cause
destruction to the print itself.
It is recommended that for both brushing methods, for the examiner to
periodically stop developing the print, examine it visually and under oblique lighting to
see if the desired effect has been produced, if the outcome of this is negative then the
examiner can resume the development technique and again periodically check to see
whether the print has been developed to their satisfaction.
With Chemical development, the specific method depends entirely on what
chemicals the examiner feels is necessary to use in their current scenarios, some
chemical developments can be conducted in-situ on scene while others need laboratory
conditions to be rendered a success.
With all chemical methods the advantages and disadvantages need to be in the forefront
of the examiners mind, as well as the practicality of their current scenario and most
importantly the safety aspects associated with using those chemicals whether in a
dynamic situation, such as being at a scene or in the controlled conditions of the
laboratory.
The final process is the recovery of the developed fingerprint. The easiest way
that this is achieved first is through the use of photography, it is up to the whim of the
examiner, and the regulations of the law enforcement agency or company in which they
are in employ of, whether they use digital photography or standard film development.
With all exhibits the photograph is usually taken at a 90o
Angle against a scale, here the
use of high contrast powder with oblique lighting, or fluorescent powder is
advantageous.

72
The other method is through the use of tape lifting, this method involves the use
of a clear adhesive polymer tape which is placed with care over the developed finger
print and then removed, in this act the eccrine sweat and sebaceous oils, with the
developing powder adhered to it is removed leaving a physical imprint on the tape
which is then mounted against a high contrast material such as white paper or plastic
and taken away for identification and analysis, this method has to be done with the
utmost care in fear of destroying the evidence, thus it is imperative that as many
photographs are obtained as photography is non-destructive70–73
.

73
3.2 Experimental Design
Controls of the researcher’s fingerprints will be taken, this will be done utilising four
methods, a UK Standard police ink plot chart showing prints for all digits and the palms
of both hands, then on a clear substrate such as a glass microscope slide all ten prints
will be deposited and photographed with oblique lighting, but no external developer.
Then the 10 prints will be developed with high contrast powder and photographed. The
researcher will deposit another 10 prints onto a clean slide and develop with fluorescent
powder and photograph. Finally with a clean slide and a final set of prints, the prints
will be developed using cyanoacrylate fuming.
This stage will provide controls for comparison against actual test data.
A proof of concept test will be conducted, this involves taking one of the
firearms to be used in the experiment, ensuring it is dry and clean, i.e. no use of
lubricants or oils present, to provide the best possible substrate. Prints will be deposited
onto the firearm as it will be handled by the researcher, and then using the processes
outlined in Chapter 2.9 attempt to develop and record the prints found on that firearm.
The actual experiment will be conducted as thus, with a variety of firearms
(outlined in Chapter 3.6), like the proof of concept the firearms will be clean and dry.
The researcher will then go through the routine of loading the firearm, chambering the
firearm and making the firearm, ready to discharge by engaging any exposed hammers
and disengaging the safety
b
.
b
Please note that the firearms will either be unloaded and the process of loading is for print deposition
only, or the firearms will have plastic, inert, training rounds which have no propellants or primers stored
in within them.

74
Through this routine the firearms will be handled with both hands of the researcher in a
variety of places allowing for sufficient print deposition.
The researcher then, while wearing 2 layers of latex or nitrile gloves will go
through the ASET make safe procedure outlined in Chapter 2.10.1, once the firearm is
declared safe the researcher, while wearing appropriate PPE, will go through the stages
of trying to visualise, develop and document or recover any fingerprint evidence found
on the firearm.
The experiment also has the potential to be run as a double blind study where the
details are identical in nature but when it comes to proceeding with the make safe
procedure, rather than the researcher rendering the firearm safe while wearing PPE, a
trained individual with no protection can go through the make safe procedure to render
the firearm safe, thus allowing for the comparison between the researchers prints and an
unknown, controls will be taken as the individual.

75
3.3 Powder Visualisation
For the experiment, five powders have been selected. These powders have been selected
based on their contrast the substrate materials so the powders are inherently bright or
dark in nature, each powder will have its own dedicated fibre brush for deposition.
The deposition method of the powder onto the substrate will be through rotating
the brush around it’s Y axis, rather than actually brushing over the latent print, this
method is being utilised as it poses minimum risk to causing damage to the fingerprint.
Powder Type/Model
Number
Amount
Aluminium/TFP0102 60g
Bi Magnetic/TFP0151 30g
Black/TFP0100 30g
Fluorescent Powder 30g
White Magnetic 50g
Table 6: Table of Powders selected for experiment and associated weights
3.4 Chemical Visualisation
The chemical visualisation method that appears to be the most suited method would be
that of cyanoacrylate fuming.
The fuming will be conducted in a standard Temperature and Pressure oven
heated to 120o
C with a Relatives humidity of 80%.
The fuming was conducted at Manlove Forensics in Wantage Oxfordshire.

76
3.4 Recovery Methods
The method utilised in the recovery of the developed latent print will be that of tape
lifting, this method will be done after the print has been photographed in situ, the
method involves using adhesive tape, the tape is laid gently over the print and then
removed and attached to a backing of appropriate contrast for comparison.
The Tape used will be ‘J-Lar’ tape, a common tape found in forensics labs, also
the background will be a clear acetate sheet, this then allows for coloured backgrounds
to be inserted behind the acetate to create the optimum amount of contrast for
photography. As well as using Tape lifts, the use of Gel lifters will be used, these lifters
work along the same principles as a standard Tape Lift.
3.5 Firearms Used
The firearms that will be acting as the test subjects, were selected for the following
criteria; first they all establish different constituent materials thus giving a large sample
range to experiment with, and also these firearms provide a general cross section of
firearms recovered from crime scenes or recovered while in the process of being
smuggled into the United Kingdom.
The firearms consist of two self-loading pistols, one revolver, one shotgun, one
submachine gun and two assault rifles.
The firearms will not be used for the cyanoacrylate fuming as they have been
loaned for the experiment, instead of full firearms, components from firearms have been
selected. Both the firearms and the components are listed in tables 7 and 8 below.

77
Type Name Calibre
Constituent
Materials of
External
Components
Self-Loading Pistol Glock 17
9mm Luger (9 x
19mm)
Polymer
Self-Loading Pistol Colt 1911 .45 ACP
Steel (Treated),
Plastic
Revolver
Smith & Wesson
.357 Magnum
.357 Magnum
Steel (Treated),
Wood
Sub-Machine Gun
Heckler & Koch
MP5
9 x 19mm PB Polymer
Shotgun Mossberg 12 Bore Wood, Steel
Assault Rifle AK-47 7.62 x 39mm Wood, Steel
Assault Rifle
AR-15 (M-16
Variant)
5.56 x 45mm Steel, Polymer
Table 7: Table listing firearms for powdering during experimentation
Component Firearm Type Firearm Calibre
Constituent
Material
Foregrip Assault Rifle L1A1 SLR 7.62 x 51mm Polymer
Magazine Assault Rifle L1A1 SLR 7.62 x 51mm Steel
Magazine Assault Rifle AK-47 7.62 x 39mm
Bakerlite
Plastic
Pistol Grip
Sub-Machine
Gun
MP5 9 x 19mm PB Porous Polymer
Top Cover Assault Rifle AK-47 7.62 x 39mm Steel
Foregrip Assault Rifle AK-47 7.62 x 39mm Wood
Foregrip Assault Rifle AK-47 7.62 x 39mm
Bakerlite
Plastic
Cocking
Handle
Assault Rifle
(Airsoft
Variant)
AR-15
5.56 x 45mm
(6mm Airsoft
Variant)
Plastic (Usually
Steel)
Table 8: Components to be subjected to Cyanoacrylate fuming at Manlove Forensics

78
3.6 Classification and Comparison
The pattern of human fingerprints comes in many different forms, these forms are;
loops, arches and whorls. These patterns will occur at different frequencies though out
the population, this is due to biological factors.74
Approximately sixty percent of the population are thought to possess the loop
pattern, making it the most common, with Whorls covering thirty five percent and
Arches making the final five percent, this figure comes from work done by Badawi et
al, and may only cover the American population.75
These groups can be further broken down into; Radial and Ulnar loop, Plain and Tented
arch, Plain, Central Pocket, Double Loop and Accidental Whorl.
A loop pattern can be classified if a minimum of one ridge entering from the
side, curving around the volar pad and exiting on the same side as the entrance. As well
as this it must also contain; one delta, a core, a minimum ridge count of one, and at least
one recurving ridge that flows between the delta and the core.
Radial and Ulnar loops are distinguished by the direction of the glow of ridges.
Radial loops are named as such as they open in the direction of the Radial bone in the
arm, while Ulnar loops open in the direction of the Ulnar bone.
Radial loops are most commonly found on the index finger.
Plain arches have ridges that flow from one side of the pad to the other, rising
smoothly in the middle, almost like a bell curve, whereas tented arches have either, a
central ridge thrusting upwards or ridges that meet at a ninety degree angle or less at the
arch.
A Plain Whorl, the simplest of the four, should have two deltas and a minimum
of one ridge that encircles the core. If drawing and imaginary line to connect the deltas,

79
one encounters a ridge encircling the core, then that is the distinguishing feature of a
plain Whorl.
A Central Pocket Whorl comprises of an imaginary line connecting the two deltas,
similar to a plain whorl, but it does not encounter the ridge encircling the core.
A Double Loop, is exactly as the name suggests, a Whorl containing two loop patterns
in a combination and finally Accidental Whorls consist of two or more pattern types or
a pattern type that does not fit into any of the categories.76
Figure 26: The main Fingerprint types classified by the FBI77
and used worldwide
As the fingerprints that are being deposited, developed, recovered and compared are that
of the researcher, as mentioned previously in the experimental design, control
fingerprints will be taken and the recovered prints will be compared, this could be done
with the use of either enlarged photographs, or utilising a comparison microscope to
analyse the experimental prints and the control prints this method is very common in the

80
United Kingdom, and is usually conducted after the prints have been submitted to a
database search.78

81
Chapter 4: RESULTS
4.1 Control Fingerprints
A scientific control is an experiment or observation designed to minimize the effects of
variables other than the single independent variable. This increases the reliability of the results,
often through a comparison between control measurements and the other measurements.
Scientific controls are a part of the scientific method.
The primary control for the experimental method are the fingerprints of the researcher.
These fingerprints were obtained by depositing them on a clear flat surface, a microscope slide.
These were then developed using aluminium Fingerprint powder and lifted using Gel Lifters.
These control prints would be the standard of comparison for the rest of the experiment.
After the prints were lifted they identified and were graded using the Bandey Scale79–81
, shown
below.
Grade Comments
0 No development
1 No continuous ridges. All discontinuous, or dotty
2 One-third of mark, continuous ridges
3 Two-thirds of mark, continuous ridges
4 Full Development. Whole Mark Continuous Ridges
Table 9: Bandey Scale, used to scale the development of fingerprints

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