Transcript Chapter 14
Chapter 14
Fingerprints
Background Info.
Bertillon’s system of anthropometry
was the 1st criminal identification
method
It was used for 20 years, but the Will
West situation proved it to be
inaccurate
Chinese used fingerprints to sign
documents 3,000 years ago!!
Important People
Henry Fauld (1880)
Said that skin
ridge patterns
could be used to
identify criminals
He was ignored
Francis Galton (1892)
Published Finger
Prints (1st book on
the topic)
3 Patterns:
Loops
Whorls
Arches
Sir Edward Henry (1897)
Developed the
classification
system used today
The 3 Principles of
Fingerprints
1.
A fingerprint is an individual
characteristic no two have
identical ridge characteristics
**Ridge Characteristics (minutiae)**
Endings
Enclosures
Bifurcations (branching)
2. Fingerprints remain unchanged
during a lifetime
Dermal papillae determine
the form & pattern
Develop in the fetus & never
change except to grow
**John Dillinger**
Gangster
used acid to destroy his prints
unsuccessful
3. Fingerprints have ridge patterns
that are classified by:
Loops 60-65%
Whorls 30-35%
Arches 5%
Types of Ridge Patterns
1. Loops
A.
B.
Ridge patterns that enter &
exit on the same side of the finger
Ulnar Loop loop comes from the
little finger
Radial Loop comes from the
thumb
2. Whorls
Ridge patterns that are
somewhat circular in nature
A. Plain Whorls must have one ridge
that makes a complete
circuit
spiral, oval, or circular
B. Central Pocket Loop same as above
C. Double Loop 2 loops in one
print
D. Accidental contains 2 or
more patterns
or a pattern not
covered
3. Arches
Ridge patterns that enter
on one side of the finger and exit
on the other
A. Plain Arch ridges rise in the
center in a wave-like
pattern
B. Tented Arch sharp rise
Primary Classification
Based on Sir Henry’s original system
Look for the presence or absence of
a WHORL
Each whorl gets a number value and
then a ratio is set up
The Ratio
R. Index + R. Ring + L. Thumb + L. Middle + L. Little
R. Thumb R.Middle R. Little
L. Index
L. Ring
Number Values
1st Pair = 16
2nd Pair = 8
3rd Pair = 4
4th Pair = 2
5th Pair = 1
Arch/Loop = 0
*Now add 1 to both numerator &
denominator = primary classification*
Detecting Fingerprints
A.
B.
Latent Prints invisible
left by sweat & oils
Visible Prints left when fingers
touch a colored
substance
blood, ink, paint
C.
Plastic Prints impressions left
on soft material
putty, wax, soap,
dust
Developing Latent
Fingerprints
A. On Non-absorbent and
Hard Surfaces
Glass, mirrors, tile, plastic, etc.
1.
Powders adhere to sweat & oil
2.
Super Glue Fuming fumes stick to
print & turn it
white
3.
Reflected Ultraviolet Imaging
System
RUVIS
Locates prints without
powders or chemicals
B. On Porous and Soft
Substances
1.
Paper, cardboard, cloth, etc.
Iodine Fuming sublimation of
iodine (solid gas)
produces fumes that
react with print
short lived
2.
Ninhydrin
reacts with amino acids
in sweat
turns purple/blue
develops prints up to
15 years old
3.
Physical Developer
last resort b/c it washes
away proteins
silver nitrate based
develops prints on articles
that were wet at one time
Preservation of Prints
Photograph the print
Transport small objects with prints to
crime lab protect with cellophane
Lift print with tape if on large or
immovable objects
Digital Imaging
Using computer software to enhance
a print
Adjusts color, brightness, & size
Compares 2 prints side-by-side &
looks for common features