Fingerprint Introduction and
Types
Unit III
Days 1 and 2
Alphonse Bertillon - 1883
• He developed the 1st
systematic personal
id system.
• His identification
system was called
anthropometry.
• It required detailed
photographs and
precise body
measurements.
Anthropometry
• The system rested on the idea that
the dimension of the human bone
system remained fixed from the
age of 20 until death.
• He claimed that skeletons were so
diverse that no two could have
exactly the same measurements.
• Involved 11
measurements…height, width of
head, length of left foot, etc…
Francis Galton Challenges Bertillon
• Building on the work of
several other scientists,
Galton publishes a famous
book called Finger Prints
in 1892.
• He discussed the anatomy
of prints and suggested
they could be classified into
categories.
• He also suggested that
prints remain unchanged
throughout one’s lifetime.
Bertillon’s System Falls - 1903
• Will West, a convict, arrives
at Fort Leavenworth
Prison.
• At check-in, guards notice
that they already have a
William West in custody.
• The two convicts looked
like twins. Their photos
and body measurements
looked too similar to be
distinguished from one
another.
Fingerprints make an appearance
in the U.S.
• After the Will West incidence and more research
was done, the FBI adopted a fingerprinting
system and classification system in 1924.
• All fingerprint records were merged into one
central located with the FBI.
Fundamental Principles of
Fingerprints
#1 Fingerprints are classed as individual evidence.
#2 Prints do not change.
#3 Prints can be classified by their ridge
characteristics.
Fundamental Principles of
Fingerprints
Number 1: Fingerprints are classed as individual evidence
• During the past 110 years and over 50 million prints, no
2 prints have been found to be identical.
• The individuality of a prints is NOT determined by its
general shape or pattern, but rather by it’s ridge
characteristics.
• Ridge patters are also called minutiae.
• In order for prints to match, they not only have to display
the same ridge patterns, but the patterns have to be in
the same location.
Ridge Characteristics - Identifying
• The average print has over 150 identifiable
ridge characteristics.
• Most prints found at crime scenes are
PARTIAL prints…so how many ridge
characteristics are needed to say that 2
prints are identical?
• Still debated…the range is 8-16. U.S.
typically uses 12.
Fundamental Principles of
Fingerprints
Number 2: Fingerprints remain unchanged
throughout a lifetime.
Let’s look at how they’re are formed:
Cross-section of Human Skin
Epidermal
Layer
Papillae
Layer
Sweat Pores
Ridge Lines
Dermal
Layer
Sweat Gland
Structure Purposes
Papillae:
• This layer of the skin separates the dermal
and epidermal layers.
• Determines the shape of the ridge
patterns.
• Once this layer develops in a fetus, it
remains unchanged, except for enlarging
during growth.
Structure Purposes
•
•
•
•
Sweat Glands and Pores:
The sweat glands produce oils, water and salt
through the sweat pores.
The liquids deposited by these ducts are left on
the surface (epidermis) of the finger.
When you touch something, that liquid leaves a
pattern of your finger’s ridge lines on the surface
of the object.
Prints left this way are invisible to the eye and
are called LATENT PRINTS.
A Closer Look at Ridge Patterns
Can you really remove your
fingerprints?
• You could cut off your prints…but you
would have to go all the way down to the
papillae layer, leaving a scar.
• Your print then becomes a very identifiable
scar pattern.
• What about acid? Gangster John Dillinger
tried to do this…
John’s prints from the morgue…
Fundamental Principles of
Fingerprints
Number 3: Prints can be classified into categories.
• Three main classes: loops, arches and whorls.
• 60-65% of the population have loops, 30-35%
have whorls and about 5% have arches.
LOOPS
• It must have one or more ridges entering from one side
of the print, recurving and exiting from the same side.
• If it opens toward the little finger, it is called an ulnar
loop.
• If it opens toward the thumb, it is called a radial loop.
• The main pattern that makes up the “loop” is surrounded
by more lines, called type lines.
• All loops have at least 1 delta, which is a triangular area
usually shaped like a silt formation near the mouth of a
river flowing into the sea.
• All loops have a core. The core is the center of the
“loop” pattern.
• The distance between the core and the delta is often
used to identify a print.
Loop Examples
Loop Core and Delta
Can you find the delta and core in
this picture?
WHORLS
Whorls are divided into 4 categories:
Plain whorl
Central pocket loop whorl
Double loop whorl
Accidental whorl
Plain Whorl
Guidelines
• Must have 2 deltas
• Must have at least 1 ridge that makes a
complete circuit. It can be in the form of:
-A spiral
-An oval
-Other variety of a circle
• An imaginary line is drawn between the 2 deltas,
and it touches any part of the spiral portion.
Plain Whorl Example
Do you see that the
line from delta to
delta is touching
the spiral portion on
the print?
Central Pocket Loop Whorl
Guidelines
Same as the plain whorl
EXCEPT:
If an imaginary line is drawn between the 2
deltas, it does not touch any part of the
spiral portion.
Central Pocket Loop Whorl
Example
Notice that the line
from delta to delta
is NOT touching
the spiral portion on
the print?
Double Loop Whorl
Guidelines
• It has 2 loops within 1 print.
• Therefore, it will have 2 cores and 2
deltas.
Double Loop Whorl Example
Accidental Whorl
Guidelines
• Like all whorls, it must have a core and at
least 2 deltas.
• Often the print that is left over after a
process of elimination.
• May consist of several patterns in one
print.
Accidental Whorl Example
Arch
2 Types: Plain and Tented
Plain
•Ridges enter on one
side and leave on the
other
•Looks like a wave
•No delta
•No core
Tented
•The same as the
plain arch, except, the
center rises sharply,
more like a spike than
a wave.
Plain Arch Example
Tented Arch Example