1. Fingerprints
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2. Principles of Fingerprints
First Principle: A fingerprint is an individual characteristic; no two fingers have yet been found to posses identical ridge characteristics.
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3. 1st principle
Mathematically, the probability for the existence of two identical fingerprint patterns in the world’s population is extremely small
No two fingerprints have ever been found to be identical
Individuality of fingerprints is based on careful study of ridge characteristics, known as minutiae

4. Principles of Fingerprints
Second Principle: A fingerprint will remain unchanged during an individual's lifetime.
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5. John Dillinger
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6. The epidermis is the outer layer of skin, while the dermis is the inner layer of skin
The dermal papillae is the layer of cells between the epidermis and dermis, that is responsible for determining the form and pattern of the ridges on the surface of the skin

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8. Once the papillae develop in the human fetus, he ridge patterns will remain unchanged throughout life except to enlarge during growth
Each skin ridge is populated with pores leading to sweat glands from which perspiration is deposited on the skin.

9. Principles of Fingerprints
Third Principle: Fingerprints have general ridge patterns that permit them to be systematically classified.
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10. Three Main Types of Prints
Loops
Whorls
Arches
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11. Deltas & Cores
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12. 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
Must have one delta, which is the ridge point at or directly in front of the point where two ridge lines diverge
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16. Whorls One or more cores At least two deltas
4 groups: plain, central pocket loop, double loop, and accidental
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20. 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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21. Least common of the three general patterns, divided into two distinct groups: plain arches and tented arches
Plain arch: formed by ridges entering from one side of the print, rising and falling, and exiting on the opposite side
Tented arch is similar to the plain arch except there is a sharp up thrust or spike, or the ridges meet at an angle that is less than 90 degrees.

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