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Fingerprints Fingerprints Presentation Transcript

  • Chapter 14 Fingerprints
  • History
    • Alphonse Bertillion
      • French police expert
      • First systematic attempt at personal identification was
    • Bertillion system
      • Relied on a detailed description of the subject
      • Combined with full length and profile photographs
      • System of precise body measurements called anthropometry
  • History
    • Francis Galton
      • 1892
      • Classic textbook finger prints
    • At Galton’s insistence
      • British government adopted fingerprinting
      • Supplement to the bertillion system.
    • Next step
      • Creation of classification systems
      • Capable of filing many thousands of prints
      • Logical and searchable sequence.
    FINGERPRINTS View slide
  • History
    • Dr Juan Vucetich
      • Devised a classification system
      • Still used in most spanish-speaking countries
    • Sir Edward Henry: system used in most English-speaking countries.
    • Will West and William West case
      • 1903
      • Bertillion system could not distinguish between men
      • Fingerprinting that clearly distinguished them
    FINGERPRINTS View slide
  • History
    • Fingerprinting used by the New York city civil service commission in 1901
    • Training of American police by Scotland yard representatives at the 1904 world’s fair
  • Fingerprint Principles Reproduction of friction skin ridges Palm side of the fingers & thumbs FINGERPRINTS
  • Fingerprint Principles
    • Individual characteristic
      • Because no two fingers with with identical ridge characteristics
    • Remains unchanged during an individual’s lifetime
    • General ridge patterns that permit systematic classification
  • Principle One Individual Characteristic No Fingers Identical
  • Principle One
    • Mathematical probability for existence of two identical fingerprint patterns in the world’s population = almost zero
    • Millions upon millions of individuals who have had their prints classified
      • No two fingerprints have been found to be identical
  • Figure 14–1  Fingerprint ridge characteristics. Courtesy Sirchie Finger Print Laboratories, Inc., Youngsville, N.C.,
  • Principle One
    • Individuality of fingerprint not determined by its general shape or pattern
    • Careful study of its ridge characteristics, known as minutiae.
      • Identity, number, and relative location
      • Individuality to a fingerprint.
    • As many as 150 minutiae on the average finger
  • Principle One
    • Three year study
      • “ No valid basis exists for requiring a predetermined minimum number of friction ridge characters which must be present in two impressions in order to establish positive identification”
    • Judicial proceeding
      • Expert must demonstrate a point-by-point comparison
      • To prove the identity of an individual
  • Fingerprint Comparison Figure 14–2  A fingerprint exhibit illustrating the matching ridge characteristics between the crime-scene print and an inked impression of one of the suspect’s fingers. Courtesy New Jersey State Police.
  • Principal Two Remains Unchanged During Lifetime
  • Principal Two
    • Epidermis
      • Outer layer of the skin
    • Dermis
      • Inner layer of the skin
    • Dermal papillae
      • Layer of cells between the epidermis and dermis
      • Responsible for determining the form and pattern of the ridges on the surface of the skin
  • Principal Two
    • Dermal papillae develop in the human fetus
    • Ridge patterns will remain unchanged throughout life
    • Enlarge during growth
    • Fingerprint remains unchanged during lifetime
  • Principle Two
    • Skin ridge is populated with pores leading to sweat glands
    • Perspiration is deposited on the skin
  • Principle Two
    • Finger touches a surface
      • Perspiration
      • Oils from hairy portions of the body
      • Transferred onto surface
    • Leaves fingerprint
  • Principle Three Ridge Patterns Permit Systematic Classification
  • Principle Three
    • All fingerprints
      • divided into three classes
      • Loops
      • Arches
      • whorls
      • L.A.W.
  • Loop Patterns
  • Principle Three - Loops
    • A loop must have one or more ridges entering from one side of the print, recurving, and exiting from the same side.
      • If the loop opens toward the little finger, it is called an ulnar loop.
      • If the loop opens toward the thumb, it is called a radial loop.
  • Principle Three - Loops Figure 14–5  Loop pattern.
  • Principle Three - Loops
    • Must have one delta
    • Ridge point at or directly in front of the point where two ridge lines (type lines) diverge
  • Whorls
  • Principle Three- Whorls
    • Divided into four groups
      • Plain
      • Central pocket loop
      • Double loop
      • Accidental
    • All have type lines and minimum of two deltas
  • Whorls
    • Plain whorl and central pocket loop have at least one ridge that makes a complete circuit
    • Double loop: two loops combined into one fingerprint
    • Accidental
      • Two or more patterns
      • Or pattern not covered by the other categories
  • Plain Whorls
    • More than 1 valid delta
    • If you look at image A  you should be able to identify the two delta's. If not then look at image B and you will see that they are displayed in the red boxes.
    • Whorl: one or more ridges which make complete circuit
    • Two delta's
      • Between which an imaginary line is drawn
      • At least one recurving ridge within the inner pattern area cut or touched. 
  • Plain Whorls
  • Whorls
    • Inner area of the pattern forms circle or oval
    • Specific ridges that are making or trying to make the circle
      • Imaginary line between the two delta's (the red line in image)
      • No lines that form the circle are intersected
  • Whorls
  • Arches
  • Principle Three - Arches
    • Least common of general patterns
      • Plain arches
      • Tented arches
    • No lines that form the circle are intersected
  • Plain Arches
    • Ridges entering from one side of the print
    • Rising and falling
    • Exiting on the opposite side
    • Like a wave
  • Tented Arches
    • Sharp upthrust or spike
    • The ridges meet at an angle that is less than 90 degrees
    • Arches do not have type lines, deltas, or cores
  • Primary Classification
    • Based on knowledge of fingerprint pattern classes
    • Fingers are paired up
      • One finger in the numerator of a fraction
      • Other in the denominator
    • Presence or absence of the whorl pattern
      • Basis for the determination of the primary classification
  • Primary Classification
    • Whorl pattern
      • Any finger of the first pair value = 16
      • On the second pair value = 8
      • On the third pair value = 4
      • On the second pair value = 2
      • On the last pair value = 1
    • Any finger having a loop or arch value = 0
  • Primary Classification
    • Values for all 10 fingers totaled
    • 1 is added to both the numerator and denominator
    • Fraction obtained is primary classification.
  • Primary Classification
    • 25 percent of the population
      • 1/1 category
      • All fingers loops or arches
    • Cannot in itself unequivocally identify an individual
    • Provides the fingerprint examiner with a number of candidates
  • AFIS
  • AFIS
    • Computer to scans, digitally encodes fingerprints
    • Can be high-speed computer processed
  • AFIS
    • AFIS aids in classifying and retrieving fingerprints
      • Converts image of a fingerprint into digital minutiae
      • Contain data showing ridges at their points of termination (ridge endings) and their branching into two ridges (bifurcations).
    • Thousands of comparisons per second
    • Produces a list of file prints to be examined by a trained fingerprint expert
  • Visible & Latent Prints
  • Latent Prints
    • Invisible fingerprints
    • Finger touches a surface
    • Body perspiration and/or oils present
    • Transferred to that surface
    • Leaves impression
    • Invisible to the eye
  • Visible Prints
    • Fingers touch a surface after contact with a colored material such as blood, paint, grease, or ink
    • Plastic prints: left on a soft material, such as putty, wax, soap, or dust
    • Little problem to the investigator
    • Usually distinct and visible to the eye.
  • Detecting Prints
  • Detecting Prints
    • Hard nonabsorbent surfaces
      • Glass, mirror, tile, painted wood
      • Developed by the application of a powder
    • Porous surfaces
      • Papers, cardboard, and cloth
      • Require treatment with a chemical
  • Ninhydrin
    • Reacts chemically with trace amounts of amino acids
    • Produces a purple-blue color
    • Messy and stains skin badly
  • Physical Developer
    • Silver nitrate-based reagent
    • Used when other chemical methods are ineffective
    • Silver nitrate solution stain skin
  • Super Glue ®
    • Nonporous surfaces
      • Metals, electrical tape, leather, plastic bags
      • Fumes from the glue adhere to the print
      • Produce white latent print
    • 98 to 99 percent cyanoacrylate ester
    • Super Glue fuming
      • Fuming chamber (for up to six hours)
      • Handheld wand that heats a small cartridge containing cyanoacrylate
  • Reflected UV Imaging System
    • RUlVIS
    • No chemicals or powder
    • Locate With light source
    • investigator develops the print in the most appropriate fashion
  • Figure 14–17  Schematic depicting latent-print detection with the aid of a laser. A fingerprint examiner, wearing safety goggles containing optical filters, examines the specimen being exposed to the laser light. The filter absorbs the laser light and permits the wavelengths at which latent-print residues fluoresce to pass through to the eyes of the wearer. Courtesy Federal Bureau of Investigation, Washington, D.C.
  • Powders
    • Powders, available in a variety of colors, can be applied with a brush or magnetic wand, and adhere to perspiration and/or body oils of the print.
  • Iodine Fuming
    • Molecular iodine solid at room temperature
    • Heat iodine crystals
    • Iodine vapors
    • Combine with latent prints to make them visible
      • Iodine prints are not permanent
      • Will fade
      • Must photograph the prints immediately
  • Fluorescence
    • High sensitivity
    • New chemical techniques used to visualize latent fingerprints
    • Fingerprints treated with chemicals
      • Induce fluorescence when exposed to lasers
      • High-intensity light sources (“alternate light sources”)
      • Quartz halogen, xenon arc, or indium arc light sources.
  • Preservation of Prints
    • Visualized latent print
    • Permanently preserved
      • Future comparison
      • Possible use as court evidence
    • Photograph must be taken
      • Before any attempts at preservation
  • Transporting Prints
    • small object: preserve in its entirety.
    • large immovable objects
      • developed with a powder
      • “ lift” with a broad adhesive tape.
      • tape placed on properly labeled card
      • good background contrast with the powder
  • Digital Imaging
    • Picture converted into digital computer file
    • Help of digital imaging software
      • Enhanced for the most accurate and comprehensive analysis
    • Compare function
      • Two images side by side
      • Allows the examiner to chart the common features on both images simultaneously
  • Fingerprint Patterns
  • Taking Fingerprints
  • Summary