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Fingerprinting

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  • 1. FINGERPRINTING “dermatoglyphics”
  • 2. History of Fingerprinting
    • 1892 – Sir Francis Galton
      • published that fingerprints are unique and invariable
      • basis for modern fingerprinting science
    • 1897 – Sir Edward Henry
      • introduces the Galton-Henry classification system
    • 1901 – 1910 widespread use of fingerprints begins
  • 3. Basics of Fingerprints
    • contact surfaces of hands and feet on humans and some other animals have a series of raised patterns called friction ridges
    • identity, number and relative location of ridge characteristics individualize a fingerprint
  • 4. Basics of Fingerprints
    • friction ridges
      • formed before birth between 6 th and 13 th week of development
      • contain a single row of pores leading from sweat glands
      • if finger is bruised or cut slightly, friction ridges not permanently altered or defaced
      • serious injuries may form a permanent scar
  • 5. Basics of Fingerprints
    • prints are permanent for the life of the individual
    • NO TWO PRINTS ARE IDENTICAL
      • not even twins
      • not even on the same person – you have 10 unique fingerprints
  • 6. Transmission of Prints
    • when a finger touches a surface, the perspiration and oils from the body are transferred to the surface
    • imprints of fingerprints can be left in a soft surface
    • a mark can be made by a substance like blood or paint on the finger
  • 7. Patterns of Friction Ridges
    • three general category patterns with variations among those groups
      • arch
      • loop
      • whorl
  • 8. Patterns of Friction Ridges
    • arch – no delta(s)
      • ridge lines start from one side of the fingertip, rise at the center and exit on the other side of the fingertip
  • 9. Patterns of Friction Ridges
    • loop – 1 delta
      • ridge lines start and end on the same side of the fingertip
  • 10. Patterns of Friction Ridges
    • whorl – 2 or more deltas
      • ridge lines are circles which do not begin or end on either side of the fingertip
  • 11. arches
    • plain arch – tends to flow across print
    • tent arch – significant upthrust in print
  • 12. loops
    • radial loop – pattern area comes from the thumb side of the hand
    • ulnar loop – pattern area comes from the little finger side of the hand
    • you must know the hand on which the print comes from to label it radial or ulnar
  • 13. whorls
    • plain – delta line cuts the inner pattern area
    • central pocket – delta line doesn’t cut the inner area
  • 14. whorls
    • double – contain two core areas (and two deltas)
    • accidental – contain more than 2 deltas
  • 15. Friction Ridge Details - Typica
    • patterns of ridges that differ from one individual to the next are called the ridge details called “typica” or “minutiae”
    • experts usually require 10-12 points of similarity in typica to establish that one print matches another
    • two main kinds of typica
      • ending lines
      • bifurcations (splitting lines)
  • 16. Friction Ridge Details - Typica
    • examples of specific typica
      • ending ridge
      • bifurcation/fork
      • short ridge
      • dot
      • bridge
  • 17. Friction Ridge Details - Typica
    • examples of specific typica
      • hook/spur
      • eye/island/lake
      • crossover
      • double fork
      • triple fork
  • 18. Friction Ridge Details - Typica
  • 19. Friction Ridge Details - Typica
  • 20. Friction Ridge Details - Typica
  • 21. Identifying a Print
    • make a preliminary match by looking at the general pattern (arch, loop, whorl)
    • on the unknown print, identify at least 10 typica
    • on the known print, attempt to find all 10 typica in the same relative positions as the ones on the unknown print
    • if the typica correspond, the print is an identical match
  • 22. Making Prints Visible
    • dusting methods
      • use powders dusted over a surface
      • powder sticks to oils and perspiration that were left on the surface
        • light powders on dark surfaces
        • dark powders on light
  • 23. Making Prints Visible
    • developing methods
      • use chemicals to make prints visible on surfaces where powder may not work
        • nin-hydrin bonds to and colors amino acids left behind – works well on paper
        • iodine vapors stick to fingerprint residue on surfaces like unpainted wood
        • cyanoacrylate (super glue) vapors adhere to residue on surfaces like styrofoam, metal and plastic
  • 24. Making Prints Visible
    • developing methods
      • use chemicals to make prints visible on surfaces where powder may not work
        • fluorescence techniques
  • 25. Collecting and Saving Prints
    • dusted and developed prints should be photographed immediately
    • most prints can be “lifted” with adhesive tape or ready made adhesive sheets to preserve them
    • photographed or lifted prints can later be scanned into IAFIS
  • 26. Fingerprint Data Banks
    • 1924 – FBI Identification Division created and 750,000 prints were transferred there
    • currently FBI possesses over 250 million sets of prints
      • criminal prints –from individuals arrested or convicted of a crime
      • civil prints – from government employees and applicants for federal jobs
  • 27. Fingerprint Data Banks
    • digital system has replaced the traditional fingerprint card
    • called IAFIS – Integrated Automated Fingerprint Identification System
    • allows officers anywhere to take suspect’s prints on electronic pad or scan a lifted print in order to make a comparison