1. FORENSIC SCIENCE Prints

2. Prints Dactyloscopy: the study of fingerprints
Making Prints
Rolling prints
Modus Operandi--primary identification number
Lifting Prints
Black, white and fluorescent powder
Chemicals--ninhydrin, iodine, silver nitrate, cyanoacrylate
Other Types of Prints
Palm, lip, teeth, eye, ear, voice, shoe and feet prints

3. What is a Fingerprint?
Skin has an outer layer (epidermis) which has ridges projecting inward, and an inner layer (dermis) which has projections pressing into the spaces between ridges
A fingerprint is a pattern made by the friction ridges, which is left behind due to sweat and oil that sticks to them.
Fingerprints form during the fetal stage of development.

4. Fundamental Principles of Fingerprints
A fingerprint is an individual characteristic.
A fingerprint will remain unchanged during an individual’s lifetime.
Fingerprints have general characteristics ridge patterns that permit them to be systematically classified.

5. Ridge Characteristics
Minutiae—characteristics of ridge patterns
Ridge ending
Short ridge
Dot or fragment
Bifurcation
Double bifurcation
Trifurcation
Bridge
Island
Enclosure
Spur
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6. Fingerprint Minutiae
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7. Arch
An arch has friction ridges that enter on one side of the finger and cross to the other side while rising upward in the middle.
Types
Plain- the arch is mild
Tented- the arch is spiked upward

8. Plain arch & Tented arch

9. Loop
A loop must have one or more ridges entering and exiting from the same side it began. Loops must have one delta (a“Y” pattern from diverging ridges)
Types
Radial--opens toward the thumb
Ulnar--opens toward the “pinky” (little finger)
Which type of loop is this, if on the right hand? Left hand?

10. Whorl A Whorl has a minimum of 2 deltas. Types Plain whorl
Plain- 2 symmetric deltas and a complete ridge circuit (circular in pattern)
Central Pocket- 2 asymmetric deltas, one side appears to be stretched
Double Loop- 2 loops and 2 deltas
Accidental- a whorl that does not fit the 3 above pattern types
Plain whorl

11. Central Pocket Whorl Double Loop (whorl) Accidental whorl

12. Human population fingerprint distribution
Loops: 65%
Whorls: 30%
Arches: 5%

13. Latent Prints
Latent fingerprints are those that are “hidden” and are not visible to the naked eye. These prints consist only of the natural secretions of human skin and require treatment to cause them to become visible.
Most secretions come from three glands:
Eccrine--largely water with both inorganic (ammonia, chlorides, metal ions, phosphates) and organic compounds (amino acids, lactic acids, urea sugars)
Apocrine--secrete cytoplasm and nuclear materials
Sebaceous --secrete fatty or greasy substances.

14. Lifting Latent Prints
Developing a print requires chemicals that react with secretions that cause the print to stand out against its background. It may be necessary to attempt more than one technique, done in a particular order so as not to destroy the print.
Powders--adhere to both
water and fatty deposits.

15. Lifting Latent Prints (cont)
Ninhydrin--reacts with amino acids to produce a purple reaction.
Silver nitrate--react with chlorides to form silver chloride, a material which turns gray when exposed to light.
Cyanoacrylate--”super glue” fumes react with water and other fingerprint constituents to form a hard, whitish deposit.
iodine--fumes react with oils and fats to produce a temporary yellow brown reaction.
In modern labs and criminal investigations, lasers and alternative light sources are used to view latent fingerprints. It was first used by the FBI in Since lasers can damage the retina of the eye, special precautions must be taken and a filter used.

16. ninhydrin Fingerprint cyanoacrylate Fingerprint
Iodine Fingerprint
ninhydrin Fingerprint
cyanoacrylate Fingerprint

17. AFIS https://www.youtube.com/watch?v=ZKi1CKTRCQM
The Automated Fingerprint Identification System - a computer system for storing and retrieving fingerprints
Began in the early 1970’s to:
Search large files for a set of prints taken from an individual
Compare a single print, usually a latent print developed from a crime scene
By the 1990’s most large jurisdictions had their own system in place. The problem - a person’s fingerprints may be in one AFIS but not in others
IAFIS—the FBI’s Integrated Automated Fingerprint Identification system which is a national database of all 10-print cards from all over the country
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18. Biometrics https://www.youtube.com/watch?v=IlThIvXn2Hk
Use of some type of body metrics for the purpose of identification. (The Bertillon system may actually have been the first biometry system.)
Used today in conjunction with AFIS
Examples include retinal or iris patterns, voice recognition, hand geometry
Other functions for biometrics—can be used to control entry or access to computers or other structures; can identify a person for security purposes; can help prevent identity theft or control social services fraud.
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19. Other Prints
Foot Prints are taken at birth as a means of identification for infants.
Palm--lines can be identified and may be used against suspects.

20. Other Prints The study of lip-prints is called cheiloscopy
Lips--display one of five common patterns
Short vertical lines
Long vertical lines
Rectangular lines that may crisscross
Diamond
Branching

21. Other Prints https://www.youtube.com/watch?v=Nn-2ZEIl494
The blood vessel patterns may be unique to individuals. They are used for today various security purposes.
Teeth--bite marks are unique and can be used to identify suspects. These imprints were placed in gum and could be matched to crime scene evidence.