Fingerprinting ppt

1. Forensic Science

2.  Objectives
◦ Discuss the history of fingerprinting
◦ Discuss the characteristics of
fingerprinting
◦ Identify the basic types of
fingerprinting
◦ Describe how criminals attempt to
alter their fingerprints
◦ Determine the reliability of fingerprints
as a means of identification
◦ Explain how fingerprint evidence is
collected
◦ Describe the latest identification
technologies
◦ Determine if a fingerprint matches a
fingerprint on record
◦ Use a process of lifting a latent print
 Vocabulary
◦ Arch
◦ Core
◦ Delta
◦ Fingerprint
◦ Latent fingerprint
◦ Loop
◦ Minutiae
◦ Patent fingerprint
◦ Plastic fingerprint
◦ Ridge pattern
◦ Ten card
◦ whorl

3.  Fingerprints as a
means to identify
individuals was a
major breakthrough in
forensic science
 The objective of this
activity is to produce a
fully printed ten card,
identify your fingerprints,
and compare your
fingerprints to those of
your classmates

4. Loop

5.  New tool to solve
crimes, clear the
innocent, and convict
the guilty
Interesting fact – Identical twins have the same DNA, but has a unique
fingerprint made up of whorls, loops, or arches.

6.  Oldest known document
showing fingerprints dates
back to third century B.C.
 Earliest known record of the
study of patterns on human
hands was 1684 by Dr.
Nehemiah
 In 1788, Johann Christoph
Andreas Mayer explained
how the ridges were never
duplicated in two persons
 In 1823, Jan Evangelist
Purkyn described nine
distinct fingerprint patterns

7.  In 1879, Alphonse
Bertillon used
fingerprints to identify
criminals and was used
in 1883 to identify a
repeating offender.
 In 1902 he solved the
first murder using
fingerprints.

8.  1888, Sir Francis Galton
(who verified prints do not
change with age) and Sir
E.R. Henry developed a
classification system for
fingerprints that is still in use
today
 1891, Ivan Vucetich
improved fingerprint
collection. Noted
measurements and took all
ten fingerprint impressions

9.  1896, Sir Edmund Richard
Henry grouped fingerprints
based on whether they
had an arch, whorl, or loop
pattern.
 Each fingerprint card was
imprinted with 10
fingerprints of a person
and marked with individual
characteristics, ten card.

10.  All fingers, toes, feet, and
palms are covered in
small ridges, called
dermal, or friction ridges
 Can leave an impression
called a fingerprint
 The imprint of a
fingerprint consists of
natural secretions of
sweat glands
◦ Water
◦ Oils
◦ Salts
◦ Everyday dirt

11. Skin is divided into three layers:
 Surface is called epidermis
◦ Thin layer (skin is shed)
◦ Mostly waterproof
◦ provides protection from bacteria and
viruses
◦ Contains melanin that filters UV rays
from the sun
 The second layer is called the
dermis
◦ Provides strength and flexibility
◦ Contains nerve endings and, sweat
glands, oil glands, hair follicles, and
blood vessels
 The subcutaneous layer is the
most internal layer of the skin
◦ Provides insulation
◦ Offers protective padding
◦ Stores energy

12.  Latest information
suggests patterns are
probably formed at the
beginning of the 10th
week
of pregnancy
 Occurs at the basal layer
within the epidermis
 Occurs because the
basal layer grows faster
than the epidermis and
the dermis the layer
collapses and folds in
different patterns

13.  Named for their visual appearance
◦ Loops - 65%
◦ Whorls - 30%
◦ Arches - 5%

14.  Two things a forensic
investigator looks for:
◦ Core – is the center of a
loop or a whorl
◦ Delta – a triangular region
located near a loop
 Investigators also look at
ridge count.

16.  The basic fingerprint patterns can be further
divided.
 Whorl patterns:
◦ Plain whorl (24 %)
◦ Central pocket loop whorl (2 %)
◦ Double loop whorl (4 %)
◦ Accidental whorl (0.01 %)
 Arch patterns:
◦ Plain arch (4%)
◦ Tented arch (1%)

17. Central Pocket Loop Whorl

18. Tented Arch

19. Double Loop Whorl

20. Plain Whorl

21. Arch

22. Accidental Whorl

23.  In order to positively match a print, more
information is needed.
 Every individual has a unique fingerprint resulting
from unique ridge patterns called minutiae.
 Recognizing those details in the differences
between ridges, their relative number, and their
location on a specific fingerprint is called
fingerprint identification.
 In order to match fingerprints, a minimum number
of points of comparison are needed.

27.  Patent fingerprints
◦ Visible prints, are left on a smooth surface when blood, ink, or
some other liquid comes into contact with the hands and is
transferred to the surface.
 Plastic fingerprints
◦ Actual indentations left in some soft material such as clay, putty, or
wax.
 Latent fingerprints
◦ Hidden prints, are caused by transfer of oils and other body
secretions onto a surface. They are made visible by dusting with
powders or making the fingerprints more visible using a chemical
reaction

28.  Criminals tried to devise
ways to alter their
fingerprints
 Ex. 1930’s, John Dillinger
tried to remove his
fingerprints with acid-
>Fingerprints came back!

29.  Many experts claim fingerprint
identification is flawless
 However, humans input and
analyze data, and humans
make mistakes
 Results need to be checked
and double checked to
prevent false convictions
 One study showed that 1 in 5
investigators make a false
identification.

30.  By 1987, the FBI had 23 million criminal fingerprint
cards on file
 Had to manually search, could take up to three
months to find a match
 In 1999, the FBI develop the Integrated
Automated Fingerprint Identification System
(IAFIS or AFIS)
 Operates 24 hrs a day, 365 days a year, now
takes up to two hours
 47 million people are recorded in the data base

31.  Dusting (drinking glasses, faucets, telephones, etc) with a
fine carbon powder can make a fingerprint more visible.
 Tape is used to lift and preserve it
 Also take photo of the print
 Metal or magnetic powders can also be used
 Chemicals can also be used to make latent prints visible
◦ Ninhydrin
◦ Cyanoacrylate vapor (superglue)
◦ Silver nitrate
◦ Iodine fuming

32. Chemical Uses Application Safety Chemical Reaction Latent Print
Ninhydrin Paper Object Dipped or
sprayed and wait
24 hours
Do not inhale or
get on your skin
Reacts with amino
acids (proteins) found
in sweat
Purple-blue print
Cyanoacrylate
Vapor
Household items:
plastic, metal,
glass, and skin
Heat sample in a
vapor tent.
Do not inhale or
get on your skin;
affects mucus
membranes
Reacts with amino
acids
White print
Silver Nitrate Wood ,Styrofoam Object dipped or
sprayed in silver
nitrate
Wear gloves to
avoid contact
with the skin
Chloride from salt in
perspiration on the
print combines with
silver nitrate form silver
chloride
Black or red dish
brown print under
UV Light
Iodine Fuming Paper ,Cardboard
& Unpainted
surfaces
In a vapor tent, heat
solid iodine crystals
Toxic to inhale
or ingest
Iodine combines with
carbohydrates in latent
print
Brownish print
(fades quickly)—
Need to photograph

34.  New scanning technology
and digital system,
fingerprints can be scanned
at the rate of 500 to 1,000
dots per inch
 Start investigating trace
evidence picked up and left
behind by our fingerprints
(ex. explosives, cigarettes,
drugs)
 Biometrics is the study of
using physical traits to
identify people.