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FORENSIC SCIENCE Prints

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FORENSIC SCIENCE Prints * Kendall/Hunt Publishing Company * Prints Dactyloscopy: the study of fingerprints Making Prints Rolling prints Modus Operandi--primary ... – PowerPoint PPT presentation

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Title: FORENSIC SCIENCE Prints


1
FORENSIC SCIENCEPrints
2
PrintsDactyloscopy the study of fingerprints
  • Making Prints
  • Rolling prints
  • Modus Operandi--primary identification number
  • Lifting Prints
  • Black, white and fluorescent powder
  • Chemicals--ninhydrin, iodine, silver nitrate,
    cyanoacrylate
  • Other Types of Prints
  • Palm, lip, teeth, eye, ear, voice, shoe and feet
    prints

3
DactyloscopyThe 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

4
What is a Fingerprint?
  • Skin has an outer layer (epidermis) which has
    ridges projecting inward, and an inner layer
    (dermis) which has projections pressing into the
    spaces between ridges
  • A fingerprint is a pattern made by the friction
    ridges, which is left behind due to sweat and oil
    that sticks to them.
  • Fingerprints form during the fetal stage of
    development.

5
Fundamental Principlesof Fingerprints
  • A fingerprint is an individual characteristic.
  • A fingerprint will remain unchanged during an
    individuals lifetime.
  • Fingerprints have general characteristics ridge
    patterns that permit them to be systematically
    classified.

6
Ridge Characteristics
  • Minutiaecharacteristics of ridge patterns
  • Ridge ending
  • Short ridge
  • Dot or fragment
  • Bifurcation
  • Double bifurcation
  • Trifurcation
  • Bridge
  • Island
  • Enclosure
  • Spur

7
Fingerprint Minutiae
8
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.
  • Types
  • Plain- the arch is mild
  • Tented- the arch is spiked upward

9
Plain arch Tented arch
10
Loop
  • A loop must have one or more ridges entering and
    exiting from the same side it began. Loops must
    have one delta (aY pattern from diverging
    ridges)
  • Types
  • Radial--opens toward the thumb
  • Ulnar--opens toward the pinky (little finger)
  • Which type of loop is this, if on the right hand?
    Left hand?

11
Whorl
  • A Whorl has a minimum of 2 deltas.
  • Types
  • Plain- 2 symmetric deltas and a complete ridge
    circuit (circular in pattern)
  • Central Pocket- 2 asymmetric deltas, one side
    appears to be stretched
  • Double Loop- 2 loops and 2 deltas
  • Accidental- a whorl that does not fit the 3 above
    pattern types

Plain whorl
12
Central Pocket WhorlDouble Loop
(whorl)Accidental whorl
13
Human population fingerprint distribution
  • Loops 65
  • Whorls 30
  • Arches 5

14
Latent Prints
  • Latent fingerprints are those that are hidden
    and are not visible to the naked eye. These
    prints consist only of the natural secretions of
    human skin and require treatment to cause them to
    become visible.
  • Most secretions come from three glands
  • Eccrine--largely water with both inorganic
    (ammonia, chlorides, metal ions, phosphates) and
    organic compounds (amino acids, lactic acids,
    urea sugars)
  • Apocrine--secrete cytoplasm and nuclear materials
  • Sebaceous --secrete fatty or greasy substances.

15
Lifting Latent Prints
  • Developing a print requires chemicals that react
    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.

16
Iodine Fingerprint
17
Ninhydrin Fingerprint
18
Lifting Latent Prints (cont)
  • Ninhydrin--reacts with amino acids to produce a
    purple reaction.
  • Silver nitrate--react with chlorides 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. It was first used by
    the FBI in 1978. Since lasers can damage the
    retina of the eye, special precautions must be
    taken and a filter used.

19
Cyanoacrylate Fingerprints
20
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

21
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.

22
Other Prints
  • Ears--shape, length and width
  • Face--pictures being used in Florida to find
    criminals
  • Voice--electronic pulses measured on a
    spectrograph
  • Feet--size of foot and toes lines of the feet
  • Shoes--can be compared and identified by type of
    shoe, brand, size and year of purchase

23
Other Prints
  • Palm--lines can be identified and may be used
    against suspects.

24
Other Prints
  • Foot Prints are taken at birth as a means of
    identification for infants.

25
Other Prints
  • The study of lip-prints is called cheiloscopy
  • Lips--display one of five common patterns
  • Short vertical lines
  • Long vertical lines
  • Rectangular lines that may crisscross
  • Diamond
  • Branching

26
Other Prints
  • The use of lip prints is not yet firmly
    established in our courts.
  • Two ways to potentially use lip prints
  • 1- print patterns for identification
  • 2- chromatography to match lipstick marks

27
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.

28
Other Prints
  • The blood vessel patterns may be unique to
    individuals. They are used for today various
    security purposes.
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