INTRODUCTION TO FINGERPRINTING

Classification

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Authors: Veon and O’Boyle 2007

LOOP• LOOPS

– Comes in– Recurves– Goes back

out same side

– Usually curving around a delta

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ARCH

• ARCH– In one side– Rises– Falls– Goes out

the other side

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WHORL

• WHORL

– Ridge recurves around 2 deltas

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In Depth Classifying8-TYPES

• Looking in depth, there are really 8 basic patterns.

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LOOP-In Depth• LOOP-the ridges flow inward and then recurve in the direction of the origin. --A single delta type divergence must be present in front of the recurving ridges

• Radial Loop-Ridges flow from the recurve toward the radius or thumb side of the hand (approximately 5% of all fingerprint patterns)

• Ulnar Loop-Friction ridges flow from and recurve toward the ulna or little finger side of the hand, (Approximately 60% of all fingerprint patterns)“PU”

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Radial Loop

Ulnar Loop

ARCH-In Depth• ARCH-Ridges enter on one side of the impression and tend to flow out the other side with a rise in the center

• Plain Arch-Ridges enter, wave or rise and exit smoothly

• Tented Arch-Ridges in the center thrust upward to give an appearance similar to a tent. Inside angle is smaller than 90 degrees

• Both types of arches comprise about 6% of all fingerprint patterns 7

Plain Arch

Tented Arch

WHORL-In Depth• WHORL-At least two delta type divergences are present with recurving ridges in front of each. (whorls comprise approximately 29% of all fingerprint patterns)

• Plain Whorl-One or more ridges form a complete revolution around the center (2 deltas)

Central Pocket Loop Whorl- Some ridges form a loop pattern which recurves and surrounds a central whorl (1 delta) 8

Plain Whorl

Central PocketLoop Whorl

Additional Types

• Double Loop-Two separate loops are present, which sometimes surround each other. Sometimes called Double Loop Whorl (ying / yang)

• Accidental-Any pattern which does not conform to any of the previous patterns

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Double Loop

Accidental

BEYOND THE PATTERN

FINGERPRINT INDIVIDUALIZATION

RIDGE ENDING BIFURCATION

LAKE or ENCLOSURE DOT or ISLAND

INDEPENDENT RIDGE SPUR

BRIDGE or CROSSOVER11

BIFURCATION

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SPUR

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RIDGE ENDING

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BRIDGE

or

CROSSOVER

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LAKE

or ENCLOSURE

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DOT or ISLAND

INDEPENDENT

RIDGE

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• Just the presence of these minutia does not individualize a print

• It is the exact type of minutia as well as the minutia location that individualizes a print

• NO TWO PRINTS HAVE EVER BEEN FOUND TO HAVE THE SAME MINUTIA IN THE SAME PLACE

• Therefore, you can conclude if you are comparing two prints, and they do have the same markings in the same place you must be looking at the same print

What next...

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So how many correlations prove a match?• It was in 1918 when Edmond Locard wrote that if 12 points

(Galton's Details) were the same between two fingerprints, it would suffice as a positive identification. This is where the often quoted (12 points) originated.

• Be aware though, there is "NO" required number of points necessary for an identification.

• Some countries have set their own standards which do include a minimum number of points, but not in the United States.

• Most agencies intentionally vary the number of correlations to avoid a standard or pattern

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