Background Background InformationInformation
Each fingerprint is made up of friction ridges, that do not change over time (unless scarring occurs)
Fingerprints are formed in the wombEach fingerprint is a deposit of wastes
when a person comes in contact with a surface
98 % is water & salts, 1% oils, 1% amino acids
Prints at a Crime Prints at a Crime SceneScene
Divided into 3 typesPatent PrintPlastic PrintLatent Print
Patent PrintPatent PrintCan be seen with the naked
eyeMade by a hand that had
blood, grease, oil, or any other sticky substance on it
Plastic PrintPlastic PrintVisible to the naked eyeFormed when an
impression is made in a soft substance such as putty, glue, dust, or butter
Latent PrintLatent PrintMost common typeCannot be seen without
applying powder or chemicalsSubstances adhere to the
amino acids or oils in the fingerprint and make it visible
Patterns of Patterns of FingerprintsFingerprints
3 basic types of patternsArch : 5% of populationLoop : 65% of populationWhorl : 30% of population
Basic FingerprintsBasic FingerprintsARCH LOOP WHORL
Plain Arch Left Radial Loop
Plain Whorl
Tented Arch Left Ulnar Loop Central Loop Whorl
Right Radial Loop
Double Loop Whorl
Right Ulnar Loop
Accidental Whorl
The ArchThe ArchFormed when the ridge lines
go from one side, rises in the middle, and leaves on the other side (like a wave)
Tented arches are more pointedNo ridgecount
The LoopThe LoopRidge lines enters & exits on the
same side of the fingerType is determined by the
direction the ridges come & leavesIf it is from the thumb-side of the
finger, it is called a RADIAL LOOPIf it is from the little finger side it
is called an ULNAR LOOP
The DeltaThe DeltaWhorls are subdivided using a
ridge characteristic called a DELTA
DELTA: Triangle pattern (ridge forks & nearby ridge)
Whorls have 2 deltas, loops have 1 delta & arches have 0 deltas
Ridge Ridge CharacteristicsCharacteristics
BIFURCATION (or fork): ridge splits into 2 friction ridges
ENCLOSURE: forms an ovalENDING RIDGES: ridges
that stop abruptly
Ridge Ridge Characteristics Characteristics
ContinuedContinuedSHORT RIDGES: begin & end
abruptly, traveling a short distance
RIDGE DOT: isolated ridge that’s length is approximately its width
Identifying Identifying FingerprintsFingerprints
8-12 points of comparison must be in common to declare the 2 prints a match
When a partial print is available, as many characteristics must be matched as possible
Characteristics can be matched to the AFIS (Automated Fingerprint Identification System)
Dusting fo r FI ngerpr ints
W O O D M E TA L P L A S TIC G L A S S TIL E
N O N P O R O U SS U R F A C E S
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