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