Chapter 4 - Fingerprints

1
Chapter 4 - Fingerprints

• Fingerprint

An imprint made by ridge patterns on the tip of a
finger
2
Fundamental Principles of Fingerprints

• A fingerprint is an individual characteristic.
• A fingerprint will remain unchanged during an
  individuals lifetime.
• Fingerprints have general characteristic ridge
  patterns that permit them to be systematically
  classified.

3
Ridge Characteristics
Minutiaecharacteristics of ridge patterns

• Ridge ending
• Short ridge
• Dot or fragment
• Bifurcation
• Double bifurcation
• Trifurcation
• Bridge
• Island
• Enclosure
• Spur

4
Classification of Fingerprints

• Loops (60-70 of prints have loops)
• Whorls (25-35 of prints have whirls)
• Arches (least common, 5 of prints have arches)

5
Loop

• A loop must have one or more ridges entering and
  exiting from the same side. Loops must have one
  core and one delta.
• Types
• Radialopens toward the thumb
• Ulnaropens toward the pinky (little finger)

Which type of loop is this? Is it on the right
hand? Left hand?
6
Loop
Radial Loop
One core One delta
Which hand?
7
Whorl

• A plain or central pocket whorl has at least one
  ridge that makes a complete circuit. A double
  loop is made of two loops. An accidental is a
  pattern not covered by other categories. Whorls
  have at least two deltas and a core.
• Types
• Plain
• Central Pocket
• Double Loop
• Accidental

8
Whorl
4 Types
Plain
Central Pocket
Double loop
Accidental
The central circular ridge is touched
The central circular ridge is NOT touched
More than 2 deltas
2 distinct loops with 2 distinct shoulders
9
Whorl
What type of Whorl?
Plain
Central Pocket
Double Loop
10
Arch

• An arch has friction ridges that enter on one
  side of the finger and cross to the other side
  while rising upward in the middle. They do NOT
  have deltas or cores. Types
• Plain
• Tented

11
Arch
2 Types
Plain Arch
Tented Arch
12
Frequency of Fingerprint Patterns
Loops Loops Whorls Whorls Arches Arches
ulnar radial plain other plain tented
60 5 20 10 4 1
13
Primary Classification
The HenryFBI Classification Each finger is given
a point value


Right
Left
14
Primary Classification
Assign the number of points for each finger
that has a whorl and substitute into the equation

right right left left
left index ring thumb
middle little 1

right right right left
left thumb middle little
index ring 1

That number is your primary classification number
15
Avoid Partial Prints
GOOD PRINTGet as much of the top part of your
finger as possible!
16
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 patterns name.
17
Identify each fingerprint pattern.
A
Left Hand
?
B
Right Hand
D
C
Right Hand
E
Right Hand
Left Hand
18
Ridge Classification (Individualization)
You have learned how to classify fingerprints
according to general patterns of groups, but to
individualize them, must use the details of the
ridge characteristics.
Minutiaecharacteristics of ridge patterns
19
Is it a match?

• There are at least 150 individual ridge
  characteristics on the average fingerprint.
• If between 10-16 specific points of reference for
  any two fingerprints identically compare, a match
  is assumed.
• Identify the 12 characteristics on the
  fingerprint.

20
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 to make a unique ID.

21
Comparison
Bridge
Dot
Island
Bifurcation
Core
A scar
Double bifurcation
Delta
Ridge ending
Spur
22
Fingerprints and the Law

• In judicial proceedings, comparison must be made
  for at least 12 different points to be considered
  a match.
• Automated Fingerprint Identification System
  AFIS - AFIS is a computerized system capable of
  reading, classifying, matching, and storing
  fingerprints for criminal justice agencies. 

23
John Dillingers Fingerprint Card
Public Enemy No. 1
24
Find at least 12 fingerprint characteristics

• On your own identify as many characteristics as
  you can

25
Dactyloscopy The study of fingerprints

• Historically
• William Herschelrequired Indians to put their
  fingerprints on contracts, and also as a means of
  identifying prisoners
• Henry Fauldsclaimed that fingerprints did not
  change over time and that they could be
  classified for identification
• Alphonse Bertillonproposed body measurements as
  a means of identification termed anthropometry
• Francis Galtondeveloped a primary classification
  scheme based on loops, arches and whorls.
• Edward Richard Henryin collaboration with Galton
  instituted a numerical classification system
• Juan Vucetichdeveloped a fingerprint
  classification based on Galtons that is used in
  Spanish-speaking countries

26
Will West
William West
27
Types of Prints

• Plastic prints (indented or molded) 3-D print
  made as indentation in soft material
• Visible prints left by finger that has touched
  blood, paint, ink
• Latent prints made by deposit of perspiration or
  body oils. Invisible until developed

28
Latent Prints

• Latent fingerprints are those not visible to the
  naked eye. These prints consist of the natural
  secretions of human skin and require development
  for them to become visible.
• Most secretions come from three glands
• Eccrine sweat glandlargely water with both
  inorganic (ammonia, chlorides, metal ions,
  phosphates) and organic compounds (amino acids,
  lactic acids, urea, sugars). Most important for
  fingerprints.
• Apocrinesecrete pheromones and other organic
  materials.
• Sebaceoussecrete fatty or greasy substances

29
Latent Prints
Skin
sweat pore
Epidermis
sweat gland duct
Sebaceous gland
Dermis
Eccrine sweat gland
Apocrine sweat gland
Subcutaneous layer
Hair follicle
30
Developing Latent Prints

• Developing a print requires substances that
  interact with secretions that cause the print to
  stand out against its background. More than one
  technique may be necessary.
• Methods to develop latent prints fall in 3 groups
• Physical techniques
• Chemical techniques
• Instrumental techniques
• 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

31
Developing Latent Prints Methods

• 1. Powdersadhere to both water and fatty
  deposits. Choose a color to contrast the
  background- white powder for dark colored
  surfaces- black powder for light colored
  surfaces- Bichromatic (grey) for either light or
  dark- magnetic powder for rough surfaces

Best on hard, non-absorbant surfaces
32
Developing Latent Prints Methods

• 2. Iodinefumes react with oils and fats to
  produce a temporary yellow brown reaction.

Best on soft, porous surfaces
33
Developing Latent Prints Methods

• 3. Ninhydrinreacts with amino acids to produce
  a purple color. Good for clothing and paper.

Best on paper and porous surfaces
34
Developing Latent Prints Methods

• 4. Silver nitratereacts with chloride to form
  silver chloride, a material which turns gray when
  exposed to light.

35
Developing Latent Prints Methods

• 5. Cyanoacrylatesuper glue fumes react with
  water and other fingerprint constituents to form
  a hard, whitish deposit which becomes permanent.
  Stains and dyes can be added afterwards to
  improve visibility. Used on non porous surfaces.

Best on non- porous surfaces (glass, metals,
tapes )
36
Case Files
The Night Stalker Richard Ramirez
Jack the Knife
37
Dusting Latent Prints
38
Other Prints

• Earsshape, length and width
• Voiceelectronic pulses measured on a
  spectrograph
• Footsize of foot and toes friction ridges on
  the foot
• Shoescan be compared and identified by type of
  shoe, brand, size, year of purchase, and wear
  pattern.

39
Other Prints
Palmfriction ridges can be identified and
may be used against suspects.
40
Other Prints
Footprints are taken at birth as a means of
identification of infants.
41
Other Prints

• Lipsdisplay several common patterns
• Short vertical lines
• Short horizontal lines
• Crosshatching
• Branching grooves

42
Other Prints
Teethbite marks are unique and can be used to
identify suspects. These imprints were placed in
gum and could be matched to crime scene evidence.
43
Other Prints
The blood vessel patterns in the eye may be
unique to individuals. They are used today for
various security purposes.
44
AFIS

• The Automated Fingerprint Identification System -
  a computer system for storing and retrieving
  fingerprints
• Began in the early 1970s 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 1990s most large jurisdictions had their
  own system in place. The problem - a persons
  fingerprints may be in one AFIS but not in others
• IAFISthe FBIs Integrated Automated Fingerprint
  Identification system which is a national
  database of all 10-print cards from all over the
  country

45
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 biometricscan 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.

46
Other Prints

• For additional information about prints and
  crime, check out Court TVs Crime Library
• www.crimelibrary.com/criminal_mind/forensics/finge
  rprints/1.html

47
Probability and Statistics
Probability and Statistics is often used in
linking evidence to a suspect
Example A suspect was identified walking out of
Montville HS carrying one of the missing
Forensics textbooks. The suspect was identified
as having light brown hair and wearing a green
shirt, blue jeans, and dark colored athletic
shoes. How common are those characteristics in a
school of 1600 students?



48
Spot the difference, test your memory
http//forensics.rice.edu/html/onlineactivities.ht
ml
49
Spot the difference, test your memory
http//forensics.rice.edu/html/onlineactivities.ht
ml
50
Dillingers Fingerprint card
51
Penny Challenge
How observant are you?
52
Which is the correct penny?NOTE You cannot
look at a real penny!
53
Answer
54
Demands Constraints

• When and where do we collect?
• How do we collect?
• For what purpose?