Study Guide Unit 3
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Patent
what’s left when you have some sort of liquid on your fingers, visible
Latent
made visible by using chemicals, traces of sweat, oil or other natural secretions on the skin, not ordinarily visible
Contaminated print
visible prints transferred onto smooth surfaces by blood or other liquids
Minutiae/Galton details
Core, ending ridge/ridge ending, short ridge, fork/bifurcation, delta, hook, eye, dot/island, crossover/bridge, enclosures, specialty, enclosure, enclosure spur
John Dillinger
an American criminal who was perhaps the most famous bank robber in U.S history, he tried to burn his fingerprints off with acid, but the procedure wasn’t as successful as he hoped, he did robberies from 1933-1934
Whorls
a pattern of spirals or concentric circles, a pattern in which one of the two deltas and in at least one ridge makes a turn through one complete circuit
What is the first type of whorl in which the pattern is the generic kind?
Plain whorl
What is the second type of whorl in which two deltas and at least one ridge make a complete circuit?
Central pocket loop whorl
What is the third type of whorl in which there are two separate loop formations with two separate and distinct sets of shoulders and two deltas?
Double loop whorl
What is the fourth type of whorl in which there are two deltas and a combination of two different types of patterns?
Accidental whorl
What percent of the population has whorls?
About 30%
Loops
a pattern in which one or more of the ridges enter on either side of the impression, recurve, touch or pass an imaginary line drawn from the delta to the core and tend to go towards the same side of the impression
What is the first type of loop in which a fingerprint or palmprint pattern consists of a loop which opens toward the ulna side of the hand (toward the pinkie).
Ulnar loop
What is the second type of loop in which the pattern flows in the direction of the radius bone of the forearm (i.e., toward the thumb)?
Radiule/radial loop
What percent of the population has loops?
About 65%
Arches
a pattern in which ridges form a hill
What is the first type of arch in which the friction ridges enter on one side of the print and flow out the other side with a rise or wave in the center?
Plain arch
What is the second type of arch in which two independent ridges come together and form an angle?
Tented arch
What percent of the population has arches?
About 5%
William Herschel
began the collection of fingerprints and noted they were not altered by age
Sir Edmond Richard Henry
developed the fingerprint classification system still used in the US
How fingerprints develop
Basal layer grows faster than the layers above and below it, basal layer collapses and folds to form intricate shapes. Fingerprints are made of an arrangement of ridges, called friction ridges. Each ridge contains pores, which are attached to sweat glands under the skin.
Eccrine glands
secretes largely water with both salts and amino acids. Found on palms of hands, feet. Most important for fingerprints.
Sebaceous glands
secretes fatty or greasy substances, sprouts a hair