The Three Principles of Fingerprints K. Clark 2007

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

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

1st Principle of Fingerprints Ridge Characteristics

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

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 http://wiki.answers.com/Q/At_what_age_does_a_fetus_develop_fingerprints

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

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

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

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

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

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

Honors Forensic Science Drills How to Roll Prints http://www.youtube.com/watch?v=d7N-4UNAzsw Honors Forensic Science Drills