Fingerprints
Can be considered class evidence
until the prints are individualized.
Fundamental Principles of Fingerprints:
1.
A fingerprint is an individual characteristic; No two
fingerprints have been found to possess identical
ridge characteristics.
2.
A fingerprint will remain unchanged during an
individual’s lifetime.
3.
Fingerprints have general ridge patterns that permit
them to be systematically classified.
Principles of Fingerprinting
Third Principle: Systematic
Classification by Ridge Patterns
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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L.A.W.
LOOP
ARCH
WHORL
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In Depth Classifying
8 Types
• Looking in depth, there are really 8 basic
patterns.
8
• 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”
LOOP –In depth
Radial Loop
Ulnar Loop
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• 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
ARCH-In Depth
• 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
Plain Arch
Tented Arch
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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 WhorlSome ridges form a loop
pattern which recurves and
surrounds a central whorl (1
delta)
Plain Whorl
Central Pocket
Loop Whorl
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Additional Types
• Double Loop-Two
separate loops are present,
which sometimes
surround each other.
Sometimes called Double
Loop Whorl (ying / yang)
Double Loop
• Accidental-Any pattern
which does not conform to
any of the previous patterns
Accidental
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BEYOND THE PATTERN
First Principle: No two fingerprints have yet
been found to possess identical ridge
characteristics
RIDGE ENDING
LAKE or ENCLOSURE
INDEPENDENT RIDGE
BIFURCATION
DOT or ISLAND
SPUR
BRIDGE or CROSSOVER
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BIFURCATION
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RIDGE ENDING
16
BRIDGE
or
CROSSOVER
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LAKE
or
ENCLOSURE
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DOT or ISLAND
INDEPENDENT
RIDGE
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What next...
• 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
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Setting Up the Match
•On the next two slides you will see 2 methods of
individualizing a print
•Both methods are accepted
•The first you draw a line to the mark and name it
right there
•The second you draw a line to the mark, number
it, and name it below
•The second method is the preferred method for
court cases. In this instance they put the two
comparative prints side by side and show by
number the correlation points
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10
11
1
2
9
8
3
7
4
6
1-Independent Ridge
2-Ridge Ending
3-Bifurcation
4-Dot
5-Bifurcation
6-Lake
5
7-Crossover
8-Ridge Ending
9-Ridge Ending
10-Bifurcation
11-Ridge Ending
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