Fingerprints Flashcards
Fingerprints are formed from the ridges on the end of each finger called
Dermal Ridges
An anatomist, __________, first attempted to classify fingerprint characteristics in _____
Marcello Malpighi, 1686
In _____, British surgeon______ began to develop a system of ______
1870, Dr. Henry Faulds. identification using printer’s ink
Fingerprints have become
a legally accepted of identification method since the 1900s.
Percentage of population with fingerprints
60% loop, 35% whorl, and 5% arches
Typelines
Ridges that diverge, usually splitting around another object within the fingerprint, such as a loop.
Deltas
Ridge points found nearest the point at which type lines diverge.
Core
the approximate center of the fingerprint pattern
Plain Arch
ridges enter from one side of a print and exit on the other without much variation or interruption
Tented Arch
sharp rise and fall in the center
Radial Loop
ridges flow towards the thumb
Ulnar Loop
ridges flow towards the little finger
Plain Whorl
forms a complete circle, if the line touches any part of the complete circut
Central Pocket Whorl
plain whorl, but the line does not touch any part of the complete circuit
Double Loop Whorl
More than one loop
Accidental Whorl
Doesn’t fit any classification
Radius
bone nearest the thumb
Ulna
bone nearest the small finger
Minutia
Smaller details required to identify fingerprints
Average person has
150 unique ridge details, but about 10 to 15 must be identified to match a fingerprint to a person
Patent Prints
visible prints caused by a finger (blood, ink, paint), can be taken with tape
Plastic prints
molded prints, impressions left behind in a material (wax, clay, soap), can be captured through casting
Latent Prints
Can’t see them, can be found with dusting (carbon powder for light items, aluminum powder on dark items, flourescent powders with UV) or fuming
Fuming
Iodine sublimes at room temp, which means it will change directly from solid to vapor. It dissolves in skin secretions (oils) that form on the print, resulting in a brown image of the print. Iodine fades overtime, so the print has to be photographed immediately.
Some use cyanocrglate (superglue)(used to make white prints) and ninhydrin (chemical used in amino acid detection) (purple fingerprint, reacts with amino acids and proteins present in skin secretions)
AFIS
Automated Fingerprint Identification System; stores fingerprint images & archives them, scanning.
