Forensic Aspects of Evidence
Fingerprint Identification
“Lifted” from Steve Gilbert, M.F.S., Ph.D.
History of Fingerprints
• 1684 – Nehemiah Grew reported that various
patterns were present in the fingers
• 1685 – Bidloo produced first fingerprint drawing
• 1823 – Johannus Purkinje wrote a commentary of
the skin system
• 1880 – Henry Faulds stated that chance prints at
scenes could identify perpetrator (Faulds)
History of Fingerprints
• 1892 – Francis Galton wrote his book called
“Fingerprints”. Studied over 40,000 prints and
failed to find any matches
• 1901 – Sir Edward Henry established the first
and continuing classification system
• 1902 – New York began collecting fingerprints
of job applicants
History of Fingerprints
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•
•
•
1903 – West Brothers case in Kansas
1904 – First fingerprint bureau
1905 – US Army began fingerprinting soldiers
1924 – FBI established FP system
Parts of the Hand
Distal
Inter Digital Intervals
Meta Carpal Crease
Thenar Eminence
Radial
II
III
I
Inter Digital Pads I - IV
IV Ulnar
Hypo Thenar Eminence
Proximal Traverse Crease
Distal Traverse Crease
Bracelet Crease
Proximal
Embryology
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6 weeks: pads II, III, IV
8 weeks: finger elongate, separate
8-12 weeks: pads round, separate pads
13 weeks: pads regress smaller
3-4 months: ridges form
The number ridges dictated by fullness of finger
pad
Pattern Anomalies
• Dissociation of Ridges – no ridges
• Dysplasia – Faulty development of friction skin
• Cuspal Patterns – ridges run distal to proximal
rather than side to side
Loops
Loops opening towards
the little finger is the
ulnar loop, whereas the
loop opening towards the
thumb is the radial loop.
One or more ridges enter on either side, recurve, touch or
pass an imaginary line drawn from the delta to core, and
terminate or tend to terminate on or toward the same side
the ridge or ridges entered.
Ridge Counting
Ridge count: 19
The line must touch the
ridge to be counted.
The number of ridges intervening between the delta and
the core is known as the ridge count. (yellow tick marks)
Plain Arch
Ridges enter on one side and flow or tend to flow out the
other side with a rise or wave in the center.
Tented Arch
Ridges enter on one side and flow or tend to flow out the
other side, however the ridges in the center do not. This
possesses an angle.
Tented Arch
Tented arch possessing the up-thrust.
Plain Whorls
If an imaginary line drawn
between both deltas crosses
or touches a recurving ridge
in the inner pattern area, the
pattern is consider a plain
whorl.
The plain whorl has two deltas and at least one ridge
making a complete circuit, which may be spiral, oval,
circular, or any variant of a circle.
Central Pocket Loop
The central pocket loop has two deltas and at least one
ridge which makes or tends to make a complete circuit.
The circuit may be spiral, oval, circular or any variant of
a circle. An imaginary line drawn between the two
deltas must not touch or cross any recurving ridges
within the inner pattern.
Double Loop
The double loop consists of two separate loop
formations, with two separate and distinct sets of
shoulders and two deltas.
Accidental
The accidental is a pattern consisting of a combination of
two different types of patterns, with the exception of the
plain arch, with two or more deltas; or a pattern which
possesses some of the requirements for two or more
different types; or a pattern which conforms to none of the
definitions.
Major Parts of Prints
• Pattern area: appears in a loop or whorl in which
appear the cores, deltas and ridges
• Core: approximate center of the print
• Delta: that point on a ridge at or in front of and
nearest the center of the divergence of the type
lines
Pattern Area
Core and Delta
Core
Delta
Fingerprint Classification
Henry System
Key
Major
Primary
Secondary
Subsecondary
20
M
1
U
IOI
L
1
U
IOI
final
10
Sample classification
Primary Classification
• Primary: Values of whorls
Finger value assignments:
Fingers 1 & 2: 16
Fingers 3 & 4: 8
Fingers 5 & 6: 4
Fingers 7 & 8: 2
Fingers 9 & 10: 1
• 1 is added to all primary classifications
• 1 over 1 indicates no whorls
• 32 over 32 indicates no whorls
Primary Classification
Even fingers
Odd fingers
Where whorls
appear in the
fingers, the
values are
added, even
over odd, with
1 added to the
total.
In this card, the
right hand has
16+8+4+1=29
The left hand:
16+2+1=19
Secondary Classification
• Secondary: the pattern appearing in the index
fingers
A
T
R
U
W
Arch
Tented Arch
Radial Loop
Ulnar Loop
Whorl
Subsecondary Classification
• Subsecondary: grouping according to the ridge
counts of loops and ridge tracings of whorls
Major Classification
• Major: Where whorls appear in the thumbs, the
major division reflects whorl tracings (inner,
outer, meeting)
• If loops appear in the thumbs, ridge counts are
used
Major Classification Table
Left Thumb Denominator
Right Thumb Numerator
01-11 Small………………………..[01-11, Small]
[12-16, Medium]
[17+, Large]
12-16 Medium…………………….. [01-11, Small]
[12-16, Medium]
[17+, Large]
17 or more, Large…………………..[01-17, Small]
[18-22, Medium]
[23+, Large]
Final Classification
• Final: ridge count of the right little finger.
*If not: ridge count in the left little finger
*If not: a whorl is used
* left delta to core (right hand)
* right delta to core (left hand)
Key Classification
• Key: ridge count of the first loop appearing on
the fingerprint card, exclusive of little fingers
Fingerprint Processing
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Powder and brush
Physical developer
Small particle developer
Ninhydrin
Cyanoacrylate
Iodine crystals
The following images depict laboratory practicums of
the junior Fingerprints and Impressions class.
Powder and Brush
Powder and Brush
A camel hair brush is used to apply the
fingerprint powder on suspect areas.
Powder and Brush
Once a print is developed, excess powder is
brushed away, leaving a visible print.
Powder and Brush
Here, a hinge lifter is used to lift the developed
print. Once applied, the print is preserved.
Powder and Brush
Powder and Brush
The lift needs to be one fluid motion.
Powder and Brush
Physical Developer
Documents can be washed with maleic acid
and placed into the developer (yellow bath).
Physical Developer
Physical Developer
The sample should be agitated for 5 to 15
minutes, or removed at the best print.
Physical Developer
The physical developer produces a dark
fingerprint when applied to latent prints.
Small Particle
Small particle reagent is
sprayed on areas of
suspected latent prints.
Primarily used for wet
surfaces, the reagent
dries leaving behind a
“powdered” fingerprint.
Ninhydrin
Ninhydrin is used on paper products. Purple
fingerprints are developed after drying for 36
hours; or heat can be applied to quicker results.
Ninhydrin
A household hair dryer produces enough heat.
Heat the sample approximately 2-3 minutes.
Ninhydrin
Ninhydrin developed latent fingerprints.
Cyanoacrylate Wand
The wand is heated by butane. The brass tip contains
cyanoacrylate (super glue).
Cyanoacrylate
Cyanoacrylate, or “super glue”, hardens fingerprints
into white crystalline prints. Vaporization occurs
with heat and humidity.
Iodine Crystals
Iodine can be fumed at low temperatures. Once
vaporous, it develops reddish-brown fingerprints.
Iodine Crystals
The specimen is placed into an air-tight
container along with iodine crystals.
Iodine Crystals
Iodine is supplied in glass ampules.
Iodine Crystals
The air-tight container prevents the escape
of iodine vapors.
Iodine Crystals
Heat from the hand is sufficient to vaporize
the crystals. A hair dryer produces quicker
results.
Iodine Crystals
An iodine fingerprint. Since iodine evaporates
quickly, prints should be photographed.
Post Mortem Prints
Kits are available for collecting fingerprints
from deceased persons.
Post Mortem Prints
Each finger is inked with the porelon pad.
Post Mortem Prints
The finger is then pressed into the concave
scoop which holds the print card.
Post Mortem Prints
All deceased persons should be printed.
Once buried or cremated, prints are no
longer available.
Automated Technology
Computer programs can now match fingerprints. The latent print (left) is matched to the
record print (right).
Record Fingerprints
Ten-print fingerprint card.
Major Case Prints
Major case prints represent all friction
ridge surfaces of the fingers and palm.
Major Case Prints
Right palm with both outer blades
of the hand. Palms are rolled.