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Fingerprints
 

Fingerprints

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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
      FINGERPRINTS
    • 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
    • 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
    • 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
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • Figure 14–1  Fingerprint ridge characteristics. Courtesy Sirchie Finger Print Laboratories, Inc., Youngsville, N.C., www.sirchie.com.
    • 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
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • Principle Two
      • Finger touches a surface
        • Perspiration
        • Oils from hairy portions of the body
        • Transferred onto surface
      • Leaves fingerprint
      FINGERPRINTS
    • Principle Three Ridge Patterns Permit Systematic Classification
    • Principle Three
      • All fingerprints
        • divided into three classes
        • Loops
        • Arches
        • whorls
        • L.A.W.
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • Whorls
    • Principle Three- Whorls
      • Divided into four groups
        • Plain
        • Central pocket loop
        • Double loop
        • Accidental
      • All have type lines and minimum of two deltas
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • Primary Classification
      • Values for all 10 fingers totaled
      • 1 is added to both the numerator and denominator
      • Fraction obtained is primary classification.
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • 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.
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • Reflected UV Imaging System
      • RUlVIS
      • No chemicals or powder
      • Locate With light source
      • investigator develops the print in the most appropriate fashion
      FINGERPRINTS
    • 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.
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • 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
      FINGERPRINTS
    • Fingerprint Patterns
    • Taking Fingerprints
    • Summary