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Fingerprint Patterns and Ridge Counts
Unit Two Forensic Science Notes 2.2
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Three Patterns (Classes) of Fingerprints
(Eight Types) Arch Patterns x2 Loop Patterns x2 Plain arch Radial Tented arch Ulnar (called a left or right loop if the hand from which it came is unknown) Whorl Patterns x4 Plain whorls Central pocket loops Double loops *Accidentals
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The Archs
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The Plain Arch Formed by ridges entering from one side of the print and exiting on the opposite side. These ridges rise at the center, forming a wavelike structure.
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The Plain Arch - count Connect the delta to the center Ridge Count = 0
(the delta is the center)
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The Tented Arch Similar to the arch, but there is either a sharp spike, or the ridges meet at an angle that is less than 90 degrees. The center often resembles a tent pole.
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The Tented Arch - count Connect the delta to the center
Ridge Count = 0 (the delta is the center)
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The Loops A loop must have one or more ridges entering from one side of the print, curving, and returning to the same side. If a loop opens toward the little finger, it is called an ULNAR LOOP. If it opens toward the thumb, it is a RADIAL LOOP.
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The Loop – Ridge count Connect the delta to the center core and count the number of ridges cross the line
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Whorl Patterns
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The Double Loop (A Whorl)
The DOUBLE LOOP is made up of any two loops combined into one fingerprint
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The Double Loop – ridge count
Count the ridges that cross a line drawn between the delta
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The Plain Whorl These have at least one ridge that makes a complete circuit. This ridge may be in the form of a spiral, an oval, or any circular form. A line drawn between the delta will intersect a circle
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The Plain Whorl - count Count the ridges crossing a line drawn between the delta.
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The Central Pocket Loop (whorl)
The central pocket loop pattern consists a whorl embedded in a loop formation. A line drawn between the deltae will not intersect a circle
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The Central Pocket Loop
Count the ridges that cross a line drawn between the deltae
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