Chapter 4
Do Now (5 mins)
• Fingerprints are found at a
crime scene.
• What type(s) of evidence
are fingerprints? Why?
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Fingerprints
a)Physical evidence
b)Trace evidence
Why trace?
Chapter 4
Fingerprint Principles (3)
According to criminal
investigators, fingerprints
follow 3 fundamental
principles:
Chapter 4
Fingerprint Principles (3)
1. A fingerprint is an
individual characteristic;
no two people have been
found with the exact same
fingerprint pattern.
Chapter 4
Fingerprint Principles (3)
2. A fingerprint pattern will
remain unchanged for the life
of an individual; however, the
print itself may change due to
permanent scars and skin
diseases.
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Fingerprint Principles (3)
3. Fingerprints have general
characteristic ridge patterns
that allow them to be
systematically identified.
Chapter 4
Ridges – unique patterns of lines in
fingerprints
Chapter 4
• Video #1, Video #2
Chapter 4
On Your Own…
• After watching the two videos, explain
the following statement:
• “Immigrants in Lawrence, MA have
frequently and unsuccessfully
attempted to alter their fingerprints.”
a) Why would it be so common?
b) Why is it so often unsuccessful?
Chapter 4
Do Now (5 mins)
• Can your fingerprints be
duplicated?
• Can your fingerprints be
removed?
• Explain why/why not.
Chapter 4
A Closer Look at Fingerprints
8th Grade Forensic Science
Chapter 4
Image from ftp://sequoyah.nist.gov/pub/nist_internal_reports/ir_6534.pdf
T. Trimpe 2007 http://sciencespot.net/
Ridgeology: The study of the
uniqueness of friction ridge
structures and their use for
1
personal identification.
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Fingerprints:
• made of a series of ridges and
valleys on the surface of the finger.
• Are unique because of..
a) pattern of ridges and valleys
b) minutiae points, which are points
where the ridge structure changes.
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minutiae
• are major features of a
fingerprint
Chapter 4
Automated Fingerprint Identification
System (AFIS)
http://www.fdle.state.fl.us/CrimeLab/images/fingerrint%20comparison%20for%20afis.jpg
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a computerized
system capable of
reading,
classifying,
matching, and
storing fingerprints
for criminal justice
agencies.
Comparison
There are no legal
requirements in the
United States on the
number of points.
Generally, criminal
courts will accept 8
to 12 points of
similarity.
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Try It!
1 – Blow up your balloon about halfway and twist the end to keep the
air from coming out. Do not tie it off!
2 – Use an ink pad to make a print with all of your fingers and label each
one with a permanent marker. Write your name on the balloon as well.
3 – Blow up the balloon to full size and tie the end.
4 – Analyze the fingerprints to find several ridge structures that we have
discussed. Use a highlighter to mark these structures on your “My
Prints” worksheet.
Think About It!
Which ridge structures were most common in your fingerprints?
Which ridge structures were most common in your group?
Were there any structures that were not found in any of the fingerprints?
Chapter 4
Balloon Fingerprint Activity: http://www.msichicago.org/fileadmin/Education/learninglabs/lab_downloads/fingerprint_analysis.pdf
Balloon Prints
• After putting your print on
a balloon, blow up the
balloon.
• Describe 3 structures in
your fingerprint that stand
out.
Chapter 4
Do Now (5 mins)
• How is a ridge different from
a valley?
• Name THREE things that
make your fingerprint unique
Chapter 4
Ridge Characteristics
Use these characteristics as points of identification when comparing fingerprint
samples. The more points you can find in common, the better the match!
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Ridge Characteristics
Crossover
Core
Bifurcation
(fork)
Ridge ending
Sca
r
Island
Delta
Pore
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http://cnx.org/content/m12574/latest/properties.jpg
•Two bifurcations
•One trifurcation
•One eye
•One island (dot)
•TWO deltas
Chapter 4
How many ridge characteristics can you identify in this fingerprint?
Chapter 4
http://www.dkfz.de/tbi/projects/bmcv/images/iu_it246_04s_fingerprint1.jpg
Do Now (5 mins)
• Describe the difference
between a delta and a
bifurcation.
Chapter 4
Do Now (5 mins)
• Without looking back at notes,
draw the following:
- Bifurcation
- Trifurcation
- Island (Dot)
- Eye
Chapter 4
Fingerprint Classes
There are 3 specific classes for all fingerprints based
upon their visual pattern: arches, loops, and whorls.
Each group is divided into smaller groups
as seen in the lists below.
Arch
Plain arch
Tented
arch
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Loop
Radial
Loop
Ulnar loop
Whorl
Plain whorl
Central pocket
Double loop
Accidentical
Loop
 A loop must have one or
more ridges entering and
exiting from the same side.
Loops must have one delta.
 Types
 Radial—opens toward the
thumb
 Ulnar—opens toward the
“pinky” (little finger)
 Which type of loop is this, if it
is on the right hand? Left
hand?
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- one delta
Loops
- one or more ridges that enter and leave on the
same side. for their positions related to the
radius and ulna bones.
Delta
Ulnar Loop (Right
Thumb)
Loop opens toward
right or the ulna bone.
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Radial Loop (Right
Thumb)
Loop opens toward the
left or the radial bone.
Whorls
-form a complete circuit
- have at least two deltas.
Central
Pocket
Whorl
Plain Whorl
Chapter 4
Whorls – Part 2
Double Loop Whorl
Accidental Whorl
Delta
Delta
Double loop whorls are
made up of any two loops
combined into one print.
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Accidental whorls contain two
or
more
patterns
(not
including the plain arch), or
does not clearly fall under any
of the other categories.
Arches
-simplest type of fingerprints that
are formed by ridges
- No deltas are present.
Plain Arch
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Spike or
“tent”
Tented Arches
An arch has ridges
Arch
that enter on one
side of the finger
and cross to the
other side while
rising upward in the
middle.
- NO DELTAS!
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Types:
Plain
Tented
32
Arch
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Loop
Whorl
Fingerprint Factoid
- 60% of people have loops
- 35% have whorls
- 5% have arches
Chapter 4
Fill in the following table…
Arch
Draw how
it looks.
# of deltas
present
Different
types of it
How
common?
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Loop
Whorl
Identify each fingerprint pattern.
Chapter 4
Identify each fingerprint pattern.
Chapter 4
Identify each fingerprint pattern.
Chapter 4
Right
Hand
Do Now (5 mins)
• Next slide
Chapter 4
Identify each fingerprint pattern.
Chapter 4
Identify each fingerprint pattern.
Chapter 4
It’s time to make
some prints!
Avoid
Partial
Prints
Chapter 4
GOOD PRINT
Get as much of the top part
of your finger as possible!
Directions
1st – Roll the “pad” portion of your thumb over the
ink pad from the left side of your thumb to the
right. You do not have to push down really hard!
2nd – Roll the “pad” portion of your thumb from the left side of
your thumb to the right in the correct box on your paper to make a
thumbprint.
3rd – Continue this process to make a fingerprint of all ten fingers
on the “My Prints” worksheet.
4th –Use your notes and a magnifying lens to help you figure out
what type of pattern is found in each of your fingerprints. Label
each one with the pattern’s name.
Chapter 4
Do Now (5 mins)
Why do we leave
fingerprints?
Example) smudges
on your cell phone
Answer:
Because our hands
naturally produces oils
These are called
secretions
Why Do We Have
Fingerprints?
Most secretions
come from three
glands:
1. Eccrine—largely water with
both inorganic and organic
compounds
Most important for fingerprints.
Most secretions come
from three glands:
2. Apocrine—secrete
pheromones and other
organic materials.
Most secretions
come from three
glands:
3. Sebaceous—secrete
fatty or greasy
substances.
The THREE types of
fingerprints are…
1. Loop
2. Arch
3. Whorl
Types of fingerprints
Whorl, loop, and arch
represent types of fingerprint
patterns
TYPES of fingerprints
demonstrates how prints are
left behind
Types of fingerprints
1. Exemplar prints
2. Latent prints
3. Patent prints
4. Plastic prints
With a partner…
Using a BLUE Forensic
Science book, define the 4
types of fingerprints
Exemplar prints
-fingerprints deliberately collected
from a subject
-for purposes of enrollment in a
system or when under arrest for a
suspected criminal offense
-Happens during an arrest or
during an FBI background check
Exemplar Print
Latent prints
- hidden or invisible
- usually left
accidentally
-less clarity and content
Latent prints
Patent prints
- friction ridge impressions which
are observable
-obvious examples would be
impressions from flour and dirt
- are photographed
- can be left on a surface by
materials such as ink, dirt, or
blood.
Patent prints
Plastic prints
-friction ridge impression left in a material
that retains the shape of the ridge detail.
-Example: criminal leaves his print in a
piece of clay
-Frequently seen in things like moulding
and window frames
Plastic prints
Do Now ( 5 mins)
What kind of fingerprint is a fingerprint left
in bubble gum? WHY?
What kind of fingerprint is left if you touch
a table with clean hands? WHY?
What kind of fingerprint is left if your
hands are covered in dirt? WHY?
A good fingerprint…
-square
-no smudging
-visible ridges
Practice the process…
1. Have partner touch your thumb to the ink pad
2. Have partner place your thumb on it’s SIDE (on
the nail) on the index card
3. Have partner roll your thumb “nail to nail”
4. If it’s your RIGHT hand…roll thumb LEFT to
RIGHT
5. If it’s your LEFT hand…roll thumb RIGHT to
LEFT
Practice the process…
Try each side of the index card a few times
Before moving on, Mr. Smith must verify
that your fingerprint is good enough
On Your Own…
Get a “Fingerprint Identification Card” and
take a print of each finger on your hand
Each print should have visible ridges, and
should be rolled in the appropriate direction
This is due at the end of class!
Type 1:Latent Prints
not visible to the naked
eye.
secretions of human skin
and require development
for them to become
visible.
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Developing Latent Prints
 Developing a print requires substances that interact
with secretions that cause the print to stand out against
its background. It may be necessary to attempt more
than one technique, done in a particular order so as
not to destroy the print.
 Powders—adhere to both water and fatty deposits. Choose a
color to contrast the background.
 Iodine—fumes react with oils and fats to produce a temporary
yellow brown reaction.
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Developing Latent Prints
 Ninhydrin—reacts with amino acids to produce a purple
color.
 Silver nitrate—reacts with chloride to form silver chloride,
a material which turns gray when exposed to light.
 Cyanoacrylate—“super glue” fumes react with water and
other fingerprint constituents to form a hard, whitish
deposit.
In modern labs and criminal investigations, lasers and
alternative light sources are used to view latent fingerprints.
These were first used by the FBI in 1978. Since lasers can
damage the retina of the eye, special precautions must be
taken.
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Iodine Fingerprint
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Ninhydrin Fingerprint
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Cyanoacrylate Fingerprints
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Other Prints
 Ears—shape, length and width
 Voice—electronic pulses measured on a
spectrograph
 Foot—size of foot and toes; friction ridges on the foot
 Shoes—can be compared and identified by type of
shoe, brand, size, year of purchase, and wear pattern.
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Other Prints
Palm—friction ridges
can be identified and
may be used against
suspects.
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Other Prints
Footprints are
taken at birth as a
means of
identification of
infants.
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Other Prints
Lips—display several
common patterns




Short vertical lines
Short horizontal lines
Crosshatching
Branching grooves
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Other Prints
Teeth—bite marks
are unique and can
be used to identify
suspects. These
imprints were placed
in gum and could be
matched to crime
scene evidence.
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Other Prints
The blood vessel
patterns in the eye
may be unique to
individuals. They are
used today for various
security purposes.
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AFIS
 The Automated Fingerprint Identification System - a
computer system for storing and retrieving fingerprints
 Began in the early 1970’s to:
 Search large files for a set of prints taken from an individual
 Compare a single print, usually a latent print developed from a
crime scene
 By the 1990’s most large jurisdictions had their own
system in place. The problem - a person’s fingerprints
may be in one AFIS but not in others
 IAFIS—the FBI’s Integrated Automated Fingerprint
Identification system which is a national database of all
10-print cards from all over the country
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Biometrics
 Use of some type of body metrics for the purpose of
identification. (The Bertillon system may actually have been
the first biometry system.)
 Used today in conjunction with AFIS
 Examples include retinal or iris patterns, voice recognition,
hand geometry
 Other functions for biometrics—can be used to control entry
or access to computers or other structures; can identify a
person for security purposes; can help prevent identity theft
or control social services fraud.
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More about Prints
For additional information about prints and
crime, check out Court TV’s Crime Library
www.crimelibrary.com/criminal_mind/forensics/fin
gerprints/1.html
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