Target 2-3 Tuesday, October 24, 2017 Fingerprints Target 2-3 Tuesday, October 24, 2017
Target 2-3 I can match fingerprints by developing, classifying, and analyzing fingerprint evidence.
Fingerprints are… Impressions left behind when friction ridges of human skin come in contact with smooth surfaces
Principles of Fingerprints A fingerprint is unique to an individual. Identical fingerprints have never been found.
Principles of Fingerprints A fingerprint will remain unchanged throughout the life of the individual, even as skin grows, is damaged, and heals.
Principles of Fingerprints Fingerprints have general ridge patterns that allow them to be systematically classified.
Classifying Fingerprints Look for deltas and cores Delta = small triangle in the print, formed where ridges split apart Core = small circle in the print, formed where ridges close in on themselves
Classes of Fingerprints Arches Plain Arch Tented Arch Loops Ulnar/Radial Loops Whorls Plain Whorl Central Pocket Loop Double Loop
Arches An arch is formed by ridges entering from one side of the print and exiting on the opposite side. Zero deltas Zero cores bsapp.com
Plain Arch Zero cores Zero deltas Ridges enter on one side, rise just a bit, and exit on the other side bsapp.com
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Tented Arch Zero cores Zero deltas A tented arch rises sharply upward causing the center of the print to look like a tent. Ridges bend at less than 90 degrees bsapp.com
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Loops A loop must have one or more ridges that enter from one side of the print, curve around, and exit the same side One delta Zero cores bsapp.com
Ulnar Loops An ulnar loop opens toward the little finger Print from the right hand bsapp.com
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Radial Loops A radial loop opens toward the thumb Print from the right hand bsapp.com
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Whorls One or more cores Two deltas bsapp.com
Plain Whorl Two deltas One core At least one ridge that makes a complete circuit Looks symmetrical – deltas are evenly spaced on each side of the core bsapp.com
Plain Whorl Two Deltas One Core Displays a degree of symmetry bsapp.com
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Central Pocket Loop Two deltas One core At least one ridge makes a complete circuit At least one ridge enters and exits the print from the same side Not symmetrical One delta off to the side One delta near the core bsapp.com
Central Pocket Loop Two Deltas One Core Lacks Symmetry A delta is observed near the core bsapp.com
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Double Loop Two deltas Two cores A double loop is made up of two loops combined into one fingerprint. Looks like an “S” bsapp.com
Double Loop Two Deltas Two Cores Appears to have an “S” in the print bsapp.com
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Accidental All other prints Can have any number of cores and deltas Cannot be classified as anything else bsapp.com
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