1. Whose fingerprint is it?
Target 2-4

2. Fingerprints are…
Impressions left behind when friction ridges of human skin come in contact with smooth surfaces

3. Principles of Fingerprints
A fingerprint is unique to an individual. Identical fingerprints have never been found.

4. Principles of Fingerprints
A fingerprint will remain unchanged throughout the life of the individual, even as skin grows, is damaged, and heals.

5. Principles of Fingerprints
Fingerprints have general ridge patterns that allow them to be systematically classified.

6. 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.
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7. Three Main Types of Prints
Loops
Whorls
Arches
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8. 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
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12. 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!

13. Left index finger

14. Left pinky finger

15. Right middle finger

16. Whorls
One or more cores
At least two deltas
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20. 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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23. 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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26. 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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29. 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
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33. 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

36. 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

39. 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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