Title: Chapter 6 Fingerprints
1Chapter 6 Fingerprints
- Fingerprints cannot lie, but liars can make
fingerprints. - Unknown
2Historical Development
- The oldest known documents showing fingerprints
date from third century B.C. China. - In ancient Babylon (1792-1750 B.C.), fingerprints
pressed into clay tablets marked contracts. - In 1788, Johann Mayer noted that the arrangement
of skin ridges is never duplicated in two
persons. He was probably the first scientist to
recognize this fact.
3Historical Development
- 4. Sir William Herschel (shown top right), in
1856, began the collection of fingerprints and
noted they were not altered by age. - 5. In 1888, Sir Francis Galton (shown bottom
right), and Sir Edmund Richard Henry, developed
the fingerprint classification system that is
still in use in the United States. - By 1896, all ten fingerprints were imprinted on a
card (called a ten card) of any convicted
criminals. - What major problem still existed that is
significantly improved today?
4What Are Fingerprints?
- All fingers, toes, feet, and palms are covered in
small ridges. - Natural secretions (mostly water from sweat
glands!) plus dirt on these surfaces leave behind
an impression (a fingerprint).
5Fingerprints
- The ridges are arranged in connected units called
dermal (or friction) ridges. - These ridges and the hundreds of sweat pores on
our fingertips help us grip objects. - Any time you touch something a fingerprint is
left behind.
6Because the surface area of friction ridges on
geckos feet is so dense, they can walk on
vertical glass.
7Formation of Fingerprints
- The creation of fingerprints occurs in a special
layer (the basal layer) in the epidermis where
new skin cells are produced. - The basal layer is the innermost layer of the
epidermis. - Fingerprints probably begin forming at the start
of the 10th week of pregnancy when the fetus is
about 3 inches long. - Because the basal layer grows faster than the
others, it collapses, forming intricate shapes.
8Basal Layer
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10Characteristics of Fingerprints
- There are 3 general fingerprint distinctions
- ARCH WHORL LOOP
- About 5 About 30
About 65 of the population
11Characteristics of Fingerprints
- Forensic examiners look for the presence of a
- core - center of whorl or loop
- deltas - triangular regions near a loop
- ridge count - the number of ridges from the
center of the core to the edge of the delta (p.
137)
12Characteristics of Fingerprints
- Basic patterns can be further divided (p. 138)
- Arch patterns can be
- Plain Arch (4)
- Tented Arch (1) forms an angle with a delta
- Whorl patterns can be
- Central Pocket (2)
- Double Loop (4)
- Accidental (0.01)
- Even twins have unique fingerprints due to small
differences (called minutiae) in the ridge
patterns.
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14Types of Fingerprints
- There are 3 types of prints that investigators
- look for at crime scenes
- Patent fingerprints are visible prints
transferred onto smooth surfaces by blood or
other liquids. - Plastic fingerprints are indentations left in
soft materials such as clay or wax. - Latent fingerprints are not visible but made so
by dusting with powders or the use of chemicals.
15What type and where can prints be recovered at
this scene?
A local pottery studio was robbed while the
potter was out. The thieves broke a window on
the studios front door and then reached inside
the broken window, turning the doorknob to get
in. Designs the potter had drawn for her future
creations were strewn about the room. A fresh
clay platter was torn in half. A cash register
was forcibly opened and all of the cash was
taken. The criminals left by simply opening the
back door.
16Latent Plastic
A local pottery studio was robbed while the
potter was out. The thieves broke a window on the
studios front door and then reached inside the
broken window, turning the doorknob to get in.
Designs the potter had drawn for her future
creations were strewn about the room. A fresh
clay platter was torn in half. A cash register
was forcibly opened and all of the cash was
taken. The criminals left by simply opening the
back door.
17Fingerprint Forensic FAQs
- Can fingerprints be altered?
- No, if, for example, they are removed with
chemicals, they will grow back. - Is fingerprint identification reliable?
- Yes, but analysts can make mistakes.
- Is fingerprint matching carried out by computers
in a matter of seconds? - No, but the FBIs Integrated Automated
Fingerprint Identification System (IAFIS or AFIS)
can provide a match in 2 hours for the prints in
its Master File.
18Fingerprint Forensic FAQs
- How are latent fingerprints collected?
19The Future of Fingerprinting
- New scanning technologies and digitally
identifying patterns may eliminate analytical
mistakes. - Trace elements of objects that have been touched
are being studied to help with the identification
of individuals. - To help with identification, other physical
features such as eyes and facial patterns are
also being studied. - http//school.cengage.com/forensicscience/home.htm
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