Whose fingerprint is it? Target 2-4

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.

What We Look For: Deltas & Cores Delta: Triangular point where multiple lines change direction Core: Central part of print; multiple lines go around this point. bsapp.com

Three Main Types of Prints Loops Whorls Arches bsapp.com

Loops A loop must have one or more ridges that enter from one side of the print, re-curve, and exit from the same side One Delta & One Core bsapp.com

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Ulnar and Radial Loops Simple loops ULNAR: loop enters/exits toward the pinky finger RADIAL: loop enters/exits toward the thumb We must know which finger/hand left the print in order to tell radial vs. ulnar!

Left index finger

Left pinky finger

Right middle finger

Whorls One or more cores At least two deltas bsapp.com bsapp.com

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Plain Whorl At least one ridge that makes a complete circuit The ridge may be in the form of a spiral, oval, or any variant of a circle Displays some symmetry If an imaginary line is drawn between the two deltas contained within the pattern and the line does not touch any of the spiral ridges, then the pattern is a plain whorl.

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Central Pocket Loop At least one ridge makes a complete circuit Ridges may be in the form of a spiral, oval, or any variant of a circle Two deltas If an imaginary line is drawn between the two deltas contained within these two patterns and the line touches any one of the spiral ridges, then the pattern is a central pocket loop.

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Double Loop A double loop is made up of two loops combined into one fingerprint. Two cores, two deltas Forms an “S” pattern

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Arches An arch is formed by ridges entering from one side of the print, rising slightly and exiting on the opposite side. No Deltas & No Cores bsapp.com

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Plain Arch The simplest of all fingerprint patterns; a plain arch is formed by ridges entering from one side of the print, rising slightly and exiting on the opposite side No deltas and no cores

Tented Arch A tented arch rises sharply upward causing the center of the print to look like a tent. By definition, the angle of the lines on a tented arch meets at less than a 90-degree angle. No deltas and no cores

Accidental Accidental prints are any prints that cannot be classified as arches, loops, plain whorls, or double loops Usually 1 or 2 cores Usually 2 deltas

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