Fingerprints are unique patterns of friction ridge skin that develop in fetuses and remain unchanged throughout life unless altered by decomposition. They can be classified into three basic patterns: arches, loops, and whorls, and are collected using various methods such as rolling prints and chemical enhancement. Automated systems like AFIS assist law enforcement in identifying fingerprints from crime scenes, utilizing techniques for both the development and recognition of latent prints.

1. Fingerprints

2. What are Fingerprints?
• Fingerprints are patterns of friction ridge skin.
• Fingers and palms of hands, soles of feet and are
characterized by ridges (hills) and valleys (furrows).
• Patterns form on skin surfaces early in embryonic
development and are carried through life.

3. Development of Fingerprints
• Fingerprint ridges are formed during the third to
fourth month of fetal development and their
formation completed by the sixth months.
• The ridges, thus, formed during the fetal period do
not change their course or alignment throughout the
life of an individual, until destroyed by
decomposition of skin, after death.

4. Principles of Fingerprints
Fingerprints follow three basic biological principles:
PATTERN TYPE: All fingerprints can be classified into
pattern types.
UNIQUENESS: Each fingerprint is unique, no two people
have the same fingerprints. Each person's
fingerprints differ from finger to finger. For
example your right thumb will have a different
characteristic orientation, position and
relationship to the right forefinger.
PERMANENCE: Fingerprints are unchanging from 3
months fetal life until decomposition. Scars are
the only exception to this rule, these then
become permanent themselves.

5. Fingerprint Patterns
• There are three basic patterns of fingerprints:
 Arches – can be plain or tented.
 Loops – radial or ulnar, depending on whether
direction of slope of pattern is towards inner arm
bone (radius) or outer arm bone (ulna).
 Whorls - most complex, and contain central pocket,
double loop, and accidental.

9. Collection Methods of Fingerprints
• Roll Prints
• Plain Prints

11. Henry System of Classification
• Parts of the Henry System are:
–Key
– Major
– Primary
– Secondary
– Sub Secondary
– Second Sub Secondary
– Final

13. AFIS
• Automated Fingerprint Identification Systems (AFIS)
are used by law enforcement.
• This system searches databases for 10 point set of
prints and searching large files for single prints
retrieved from a crime scene.

14. Law Enforcement Information
Systems
• FBI recently made its criminal database of
known fingerprint cards (IAFIS) available.
• Latent print examiners can search unknown
latent impressions to assist in identification of
suspects or victims.

15. Types of Fingerprints
• Three types of fingerprints encountered at
crime scenes or on evidence:
• Patent – clearly recognizable fingerprint that needs no
processing – could be in grease, blood, dirt, or oil.
• Plastic print – also called an impression or
indentation print- could be in tar, butter, silly putty.

16. Cont…
• Latent print – requires additional processing to be
rendered suitable for comparison – processing is
called development or enhancement

17. Development of Latent Prints
• Fingerprint residue, which is composed of inorganic
and organic residues, comes from eccrine glands and
from touching areas where apocrine glands in body
are before touching item
• Fingerprints can also come from touching external
sources- oils, tars, etc. and then touching surface of
object

18. Physical Methods
• Latent fingerprint powder dusting is primary method
of visualizing fingerprints.
• Black fingerprint powders generally have best results.
• Magnetic powders and brushes are now available.
• Small particle reagent (SPR) is sprayed on print and
adheres to lipids from prints.

20. Chemical Methods
• Chemical methods of techniques for visualizing
fingerprints are:
– Silver nitrate – rarely used anymore.
– Iodine fuming – very common –dirty brown
colored print and needs to photographed quickly as
it fades.

21. Cont…
– Ninhydrin – used since 1910 and is slow to react
unless heat and humidity are present – develops
bluish-purple prints.
– Cyanoacrylate (superglue) is used to fume and
yields an off white colored print – use of heat and
humidity accelerates process.

22. Cont…
• Physical Developer (PD) photographic type process
based on deposition of silver onto latent fingerprint
residue.
• US Secret Service modified procedure and uses
colloidal gold to enhance prints.
• Normally used after Ninhydrin.

23. Combination and Special Lighting
• Various types of lights are used to illuminate
fingerprints.
• Bright white light (525 nanometers), lasers, and black
lights with the use of fluorescent powders are
commonly used.

24. Bloody Fingerprints and Other
Special Situations
• Bloody fingerprints normally are not latent –
primarily composed of blood.
• Most processes for latent print chemical enhancement
do not interfere with blood collection for DNA
profiling by PCR for CODIS.
• Many bloody fingerprints are enhanced by
peroxidase- reaction chemicals

25. Cont…
• Fingerprints that are on tape, especially the sticky
side, were developed by crystal violet.
• Most common method today is sticky side powder,
which is composed of lycopodium (plant pollen) that
is mixed with detergent and water.

26. Recognition, Collection and
Preservation of Fingerprint
Evidence
• Fingerprints are among best evidence.
• Objects at a crime scene which are believed to
contain prints should be collected.
• If collection is impossible, latent development
techniques should be used.
• Photographing of developed prints is advisable.

27. Fingerprint Identification
• David Ashbaugh (1999) noted fingerprint
individuality:
– Friction ridges develop in fetuses.
– Friction ridges remain unchanged except for scars.
– Friction ridge patterns and details are unique.
– Ridge patterns vary within certain boundaries that
allow patterns to be classified.

28. Cont…
• Overall process of fingerprint examiner according to
Ashbaugh, A.C.E.V. :
– Analysis
– Comparison
– Evaluation
– Verification