Dermatoglyphics

1
Dermatoglyphics

• Introduction to Fingerprint Identification

2
Fingerprints introduction

• Start by lifting some of your own prints on a cue
  card. Do several fingers to get a representative
  sample. Consider the following questions
• What do you notice about the types of
  fingerprints? Are the general patterns? Do all of
  your fingerprints have the same pattern? Can you
  categorize patterns looking at yours, and some
  prints from people sitting next to you? Any fine
  features stand out?
• How do you think fingerprints are formed on your
  hands? What is their function? Do other animals
  have fingerprints? How are they transferred to
  other objects (i.e. what is being transferred?
  Why do your fingers leave prints?)

3
What Well Cover

• A Brief History
• Bertillon, Galton Will West
• How Fingerprints Are Formed
• Types of Prints and Minutiae
• Loops, Whorls and Arches
• Methods of Detecting, Visualizing and Lifting
  Prints
• Databases
• The Admissibility of Fingerprints

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History
5
Alphonse Bertillon

• 1883 Created the first systematic system of
  individual classification identification
• Detailed description of subject, full-length
  profile photographs a system of precise body
  measurements (anthropometry)

http//www.spsmvbr.cz/cesky/os_stranky/jedlicka/mu
zeumzla/bertilon/bertilon.html
http//criminaljustice.state.ny.us/ojis/history/me
asure.jpg
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Sir Francis Galton - 1888

• Sir Francis Galton, a British anthropologist and
  a cousin of Charles Darwin, began his
  observations of fingerprints as a means of
  identification in the 1880's.
• In 1892, he published his book, "Fingerprints",
  establishing the individuality and permanence of
  fingerprints. The book included the first
  classification system for fingerprints.

http//en.wikipedia.org/wiki/Francis_Galton
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Sir Francis Galton - 1888

• Galton's primary interest in fingerprints was as
  an aid in determining heredity and racial
  background.
• He soon discovered that fingerprints offered no
  firm clues to an individual's intelligence or
  genetic history
• He demonstrated that fingerprints do not change
  over the course of an individual's lifetime, and
  that no two fingerprints are exactly the same
• According to his calculations, the odds of two
  individual fingerprints being the same were 1 in
  64 billion.

8
Will West

• 1903 William West incident
• Fort Leavenworth prison
• New prisoner William West couldnt be
  distinguished from unrelated inmate with same
  name by anthropometry
• Discovered that their fingerprints differed

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How Fingerprints Are Formed
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Fingerprints

• A fingerprint is an INDIVIDUAL CHARACTERISTIC
• no two are alike and no two have yet been found
  to possess identical ridge characteristics.
• Fingerprints are the product of your genes as
  well as the environment of the womb during
  development in the first trimester (nutrition,
  blood pressure, contact with the womb)
• Once developed, fingerprints do not change over
  the course of your life, although they may be
  altered or scarred
• They evolved in some primates and other animals
  (e.g. koalas) for firmer grasp and resistance to
  slippage
• They are comprised of a series of lines
  corresponding to hills (ridges) and valleys
  (grooves).

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Efforts to Remove Fingerprints are Unsuccessful

• John Dillingers Prints Before and After
  Treatment with Acid

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Anatomy of the Fingerprint

• Skin is composed of layers of cells Epidermis
  (outer portion) and dermis as inner skin.
• In a cross section- a boundary of cells
  separating the epidermis from the dermis is made
  up of dermal papillae- these determine the form
  and pattern of ridges on the surface.
• Dermal papillae develop in the fetus and remain
  unchanged during life.
• Sweat glands discharge and deposit perspiration
  to the surface of the skin sweat is vital to
  the formation of latent fingerprints

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Latent Prints

• Each skin ridge is populated with a single row of
  poresopenings for ducts leading from sweat
  glands
• There are 2 types of sweat glands only those
  found on the surfaces of the hands and feet
  (eccrine glands) secrete perspiration that does
  not contain oil
• Oil in fingerprints comes from the hand
  contacting other parts of the body (e.g. face) or
  other substances containing oil
• Perspiration from eccrine glands discharges and
  deposits water (95), urea, salts and proteins
  on surface of skin.
• When the finger comes into contact with another
  surface, the water and dissolved substances are
  transferred
• This leaves an impression of the fingers ridge
  pattern (fingerprint)
• These are typically invisible to the eye and
  referred to as latent fingerprints

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Types of Prints and Minutiae
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Types of Prints
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Types of Prints

• FINGERPRINTS HAVE GENERAL RIDGE PATTERNS FOR
  CLASSIFICATION
• Divided into three classes
• LOOP
• WHORL
• ARCH
• 60-65 OF THE POPULATION HAS LOOPS
• 30-35 WHORLS
• AND 5 ARCHES

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Dermatoglyphics

• Individuality is not determined by general shape
  or pattern but by a careful study of its ridge
  characteristics
• (also called minutiae)
• Identity- number- and relative location of
  features that impart individuality.
• The features should be in the same relative
  location to one another.
• In court, a point-by-point comparison must be
  made to establish identity

http//cnx.rice.edu/content/m12574/latest/match.jp
g
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Minutiae
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Deltas and Cores

• TYPE LINES are two diverging ridges usually
  coming into and splitting around an obstruction,
  such as a loop.
• A DELTA is the ridge point nearest the type line
  divergence.
• Triangular in shape.

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Matching Minutiae
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Making Comparisons

• There are as many as 150 individual ridge
  characteristics on the average fingerprint.
• a vast majority of prints recovered from crime
  scenes are partial impressions- showing only a
  segment of the print.
• Expert has to compare a small number of ridge
  characteristics from the recovered print to the
  known recorded print.
• Criteria of individuality in court generally
  requires 8-16 matching characteristics, but often
  this number is not as important as the expertise
  of the fingerprint examiner
• 1973 International Association for Identification
  concluded it is the responsibility of the
  examiner- based upon experience and knowledge to
  establish positive identification.

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Loops

• A loop must have one or more ridges entering from
  one side of the print, recurring and exiting from
  the same side.
• If loop opens toward little finger ulnar loop
• Opens in the direction of the thumb radial loop
• ALL LOOPS HAVE ONE DELTA

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Whorls

• All whorl patterns must have type lines and a
  minimum of two deltas.
• A PLAIN WHORL and CENTRAL POCKET LOOP have at
  least one ridge that makes a complete circuit.
  This ridge may be in the form of a spiral, an
  oval, or any variant of a circular form.
• The main difference between these two patterns
  can be shown if an imaginary line is drawn
  between the two deltas contained within the two
  patterns.
• If the line touches any one of the spiral ridges,
  the pattern is determined to be a plain whorl, if
  no ridge is touched, the pattern is a central
  pocket loop.

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Plain Whorl

• In this plain whorl, the line between deltas
  touches and runs through the central pattern

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Central Pocket Whorl

• In this central pocket whorl, the line between
  the deltas does not touch any ridge formation in
  the inner part of the pattern.

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Double Loops and Accidental

• The DOUBLE LOOP is made up of any two loops
  combined into one fingerprint.
• Any print classified as ACCIDENTAL either
  contains two or more patterns (not including the
  plain arch) or the pattern is not covered by
  other categories i.e., a combination loop and a
  plain whorl or a loop and tented arch.

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Arches

• Of the two types of arches, the PLAIN ARCH is the
  simplest of all fingerprint patterns. It is
  formed by ridges entering from one side of the
  print and exiting on the opposite side. These
  ridges tend to rise at the center of the pattern,
  forming a wavelike structure.
• The TENTED ARCH is similar, but instead of rising
  smoothly at the center, there is either a sharp
  up thrust or spike, or the ridges meet at an
  angle that is less than 90 degrees.

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Databases
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IAFIS

• INTEGRATED AUTOMATED FINGERPRINT IDENTIFICATION
  SYSTEM
• Large database of fingerprint collections- using
  individual characteristics of fingerprints
  converted into DIGITAL MINUTIAE ridge endings,
  and branching.
• Location and relationship of minutiae in a
  digitally recorded geometric pattern
• A computer can make thousands of fingerprint
  comparisons in a second.
• IAFIS does not make final verification of print
  identity, but rather flags prints with the
  closest correlation to the search prints.
• ALLOWS CRIMINAL INVESTIGATORS TO SPEND LESS TIME
  DEVELOPING SUSPECT LISTS AND MORE TIME
  INVESTIGATING SUSPECTS GENERATED BY THE COMPUTER.
• Fingerprints are voluntarily submitted to the FBI
  by local, state, and federal law enforcement
  agencies. These agencies acquire the fingerprints
  through criminal arrests or from non-criminal
  sources, such as employment background checks.
  The FBI then catalogs the fingerprints along with
  any criminal history linked with the subject.

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Methods of Detection
31
Fingerprint visibility

• Latent fingerprint- earlier stated was invisible
  to the eye since they are just perspiration and
  sometimes oil.
• Composed mainly of water (95) and 5 other
  substances chemicals used to make these visible
  react with some of these substances
• Visible Prints made by fingers touching a
  surface after ridges have been in contact with
  colored material BLOOD, PAINT, GREASE, INK
• Plastic Prints are ridge impressions left in soft
  material- putty, wax, soap, or dust.
• Locating visible prints are easier being visible
  and distinct to the eye.
• Latent prints are more difficult and require use
  of technologies and techniques that will make the
  print visible.

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METHODS OF DETECTING LATENT FINGERPRINTS

• THE METHOD OF CHOICE WILL DEPEND ON THE SURFACE
  BEING LIFTED OR TESTED.
• Hard and non-absorbent surfaces (glass, mirror,
  tile, and painted wood) require different
  approaches than soft and porous- paper, cloth, or
  cardboard.
• The most challenging thing an examiner faces is
  location of latent prints.

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Visualization of Latent Prints

• On hard surfaces
• Powder
• Grey or black
• Florescent
• Magnetic
• Superglue
• Lighting Techniques

• On soft surfaces
• Iodine fuming
• Nonpermanent visualization
• Ninhydrin
• Reacts with proteins
• Gentian violet
• Binds to cells and oils on tape

Ninhydrin
34
Ultraviolet Imaging Systems

• Light sources can be used to locate prints which
  can then be enhanced and lifted using other
  methods. This saves time and energy by narrowing
  a search.
• Reflected Ultraviolet Imaging System- locates
  prints on nonabsorbent surfaces without chemical
  or powder treatments.
• When UV light strikes the fingerprint, light is
  reflected back to the viewer- differentiating the
  print from its background surface.

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Ultraviolet Imaging Systems
Untreated Oily Print on sticky side of Duct
(Duck) tape. 35mm Black and White film.Scene
Scope excels at detecting prints on surfaces that
a forensic light source would find difficult or
impossible.
Latent fingerprint on Painted Wall. Illustration
of Contrast Effect due to variation of
illumination angle. Depending on what angle the
user holds the light, a print can either appear
white or black.
36
Ultraviolet Imaging Systems

• Hand held Forensic Light Sources

37
Fingerprint Powders

• Commercially available in a variety of colors and
  textures (photographing)
• Lightly applied to nonabsorbent surfaces with
  camelhair brush will ADHERE TO PERSPIRATION
  RESIDUES AND BODY OILS.
• Black and gray for photographing on surfaces-
  produce contrast.

38
Fluorescent Powders

• Fluorescent powders that fluoresce under
  ultraviolet light- used when color or pattern of
  background obscures visibility of the print.
  (plaid, newsprint, etc).
• Prints are typically not tape lifted, but
  photographed and digitized or transferred to a
  computer for analysis

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CHEMICAL METHODS FOR VISUALIZING LATENT PRINTS

• Iodine fuming
• Iodine is a solid crystal that when heated, turns
  into a vapor without passing through a liquid
  phase
• this transformation is called sublimation.
• Suspect material is placed in an enclosed cabinet
  with iodine crystals
• Once heated, vapors fill the chamber and combine
  with amino acids in the latent print to make it
  visible.
• Iodine prints are not permanent and begin to fade
  once fuming is stopped. The print may be fixed
• IT IS NECESSARY TO PHOTOGRAPH IMMEDIATELY
• Can be fixed with 1 solution of starch in water
  applied by spraying- this will turn blue and last
  for several weeks or longer.

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Super Glue Fuming

• Super Glue fuming- works great on nonporous
  surfaces- metals, leather, plastic bags.
• Created when superglue is placed on a hot plate.
• Heating produces vapors that polymerize on the
  print.
• Fumes and object contained within an enclosed
  chamber for up to 6 hrs.
• Produces white latent print.
• The print may be enhanced with a conventional
  powder

41
Gentian Violet

• Once the standard for lifting latent prints on
  sticky surfaces like tape has now been replaced
  by a commercial product called Sticky-Side
  Powder
• The dark purple dye stains sebaceous material
  (oil) and skin cells which have sloughed off of
  the person's fingers and palms and which have
  stuck to the adhesive side where the tape was
  touched.

42
Ninhydrin

• One of the major components of fingerprints is
  amino acids. Several substances bind to them, but
  ninhydrin is particularly effective.
• It is sprayed or poured onto the evidence, and a
  permanent pink and purple fingerprint results.
• On the downside, it is toxic and causes blinding
  headaches if inhaled

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Ninhydrin Reaction
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Admissibility
45
Fingerprints and their use in court

• The low probability of 2 unrelated prints
  matching is the foundation for its acceptance in
  court
• Recall Galton said the probability that two
  fingerprints could match is one in 64 billion.
• This is supported by the millions of individuals
  who have had prints taken over the past 90 years
  in the FBI central system- no two have ever been
  found to be identical

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Fingerprints and their use in court

• Which of the Daubert Standards does fingerprint
  analysis meet?
• Subjected to peer review and publication
• The theory or technique must be falsifiable,
  refutable, and testable.
• Whether there are standards controlling the
  technique's operations.
• Expert's qualifications.
• Technique and its results be described with plain
  meaning.
• Known or potential error rate.

47
Error Rate

• A case being argued at the Supreme Court in
  Boston recently challenged the idea that
  fingerprint analysis has a zero error rate
• While testifying, fingerprint examiners give
  all-or-nothing judgments.
• The International Association for Identification,
  the oldest and largest professional forensic
  association in the world, states in a 1979
  resolution that any expert giving "testimony of
  possible, probable or likely fingerprint
  identification shall be deemed to be engaged in
  conduct unbecoming".
• Is fingerprint analysis that robust? Consider the
  following studies

http//www.newscientist.com/article.ns?iddn8011
48
Error Rate

• The FBI's Latent Fingerprint Section in Quantico,
  Virginia took a set of 50,000 pre-existing images
  of fingerprints and compared each one
  electronically against the whole of the data set,
  producing a grand total of 2.5 billion
  comparisons.
• It concluded that the chances of each image being
  mistaken for any of the other 49,999 images were
  vanishingly small, at 1 in 1097
• Critics say that showing an image is more like
  itself than other similar images is irrelevant.
  The study does not mimic what happens in real
  life, where messy, partial prints from a crime
  scene are compared with inked archive prints of
  known criminals.

http//www.newscientist.com/article.ns?iddn8011
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Error Rate

• One unpublished study may go some way to
  answering the critics. It documents the results
  of exercises in which 92 students with at least
  one year's training had to match archive and mock
  "crime scene" prints. Only two out of 5861 of
  these comparisons were incorrect, an error rate
  of 0.034 per cent.
• But evidence from qualified fingerprint examiners
  suggests a higher error rate. These are the
  results of proficiency tests in the Journal of
  Criminal Law Criminology (vol 93, p 985).
• These estimates that false matches occurred at a
  rate of 0.8 per cent on average, and in one year
  were as high as 4.4 per cent. Even if the lower
  figure is correct, this would equate to 1900
  mistaken fingerprint matches in the US in 2002
  alone.
• How reliable are fingerprint analyses? You be the
  judge!

http//www.newscientist.com/article.ns?iddn8011