1. The Three Principles of Fingerprints
K. Clark 2007

2. History of Fingerprints:
1892, Galton wrote book “Finger Prints”
Anatomy of fingerprints
Determined that no two prints were the same
A person’s prints remain unchanged
1901, US adopted fingerprinting system
1924, fingerprint collection formed at the FBI
1999, US v. Byron C. Mitchell
British government adopted fingerprinting system in addition to Bertillon’s system
FBI has the largest collection of fingerprints in the world
Case: defense argued that fingerprints are not unique – Judge ruled that fingerprints are unique and permanent

3. 1st Principle of Fingerprints:
No two people have identical fingerprints
70 billion possibilities
Individuality of a fingerprint determined by its Ridge Characteristics (Minutiae)
Identity, number, and relative location of characteristics
Approximately 150 ridge characteristics on the average fingerprint
8-16 ridge characteristics needed for ID
If two prints are to compare, they will have to reveal characteristics that not only are identical but have the same relative location to one another in a print
In a judicial proceeding, a point-by-point comparison must be demonstrated by the expert to prove the identity of an individual
Most prints uncovered are only partial prints

4. 1st Principle of Fingerprints
Ridge Characteristics

5. 2nd Principle of Fingerprints:
Fingerprints remain unchanged during an individual’s lifetime
Fingerprints are formed from friction skin ridges on the palm side of the fingers and thumbs
Also on the palms and bottoms of feet
Designed by nature to provide our bodies with a firmer grasp and a resistance to slippage
Hills – ridges, valleys – grooves, shape and dorm of the ridges that one sees as the black lines of an inked fingerprint

6. 2nd Principle of Fingerprints:
Epidermis – outer skin
Dermis – inner skin
Papilla – boundary between two skin layers
Develops in the fetus & remains unchanged
Determines the form and pattern of the ridges
Ridge patterns enlarge during growth

7. 2nd Principle of Fingerprints:
Pores – discharge and deposit perspiration
Once the finger touches a surface the perspiration is transferred onto that surface, leaving an impression of the finger’s ridge pattern
Latent Fingerprint – prints that are invisible to the naked eye

8. 2nd Principle of Fingerprints:
Can one change his/her fingerprints?
Injuries that reach to the papilla (1-2mm deep) leave permanent scars
John Dillinger – attempted to obliterate fingerprints by pouring corrosive acid on them
Presence of permanent scars merely provides new characteristics for identification
Dillinger - gangster

9. 3rd Principle of Fingerprints:
Fingerprints have general ridge patterns that permit them to be systematically classified
3 classes:
Loops
Whorls
Arches A B C

10. 3rd Principle of Fingerprints:
Loops
Ridge lines enter from one side of the pattern and curve around to exit from the same side of the pattern
60-65% of population has loops
Ulnar loop- opens towards the little finger
Radial loop – opens towards the thumb
Pics – ulnar, radial
Ulnar loop
Delta
Core
Radial loop

11. 3rd Principle of Fingerprints:
Whorls
Ridge patterns that are generally rounded or circular in shape and have two deltas
30-35% of population has whorls
Accidental – contains two or more patterns (not plain arch)
Double Loop
Plain Whorl
Central Pocket Loop
Accidental

12. 3rd Principle of Fingerprints:
Arches
Ridge lines enter from one side and flow out the other side
5% of population of arches
No cores or deltas
Plain arch
Tented arch

13. Honors Forensic Science Drills
How to Roll Prints
Honors Forensic Science Drills