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Forensic Lab Investigations

Forensic Lab Investigations. Fingerprinting. Been used for identification since the early 1900s FBI Identification division began, in 1924, with 810,188 fingerprint files Currently, more than 250 million fingerprint records. Background.

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Forensic Lab Investigations

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  1. Forensic Lab Investigations

  2. Fingerprinting • Been used for identification since the early 1900s • FBI Identification division began, in 1924, with 810,188 fingerprint files • Currently, more than 250 million fingerprint records

  3. Background • Skin on palms, fingers, and feet have tiny surface ridges • Gives traction for walking and grasping • Pattern is unique to each person

  4. Why do we leave prints? • Skin surface covered with oils, sweat, and amino acids which transfer to an object when touched • Foreign substances (oil, blood, dirt, ink, etc.) • Exact impression of surface ridge is left behind

  5. Can your fingerprints change? • No, fingerprints will always remain the same. • They may scar or have cracks. • Can be masked with super glue or burnt off, but they will return

  6. Matching Prints • There are no set matches of points that must be provided for court • The more you have the more convincing your evidence • Must show how the points match

  7. Types of Prints • Fingerprint Impression • Arch, whorl, loop • Categories: • Loop, double loop, central pocket loop, tented arch, plain arch, plain whorl, accidental

  8. In a whorl pattern, the ridges are usually circular • In a loop pattern, the ridges enter from either side, re-curve and pass out or tend to pass out the same side they entered • In an arch pattern, the ridges enter from one side, make a rise in the center and exit generally on the opposite side

  9. Tented Arch

  10. Can you identify these prints? B C A

  11. Minutiae (Galton) Points • Ridge characteristics that go into a little more detail than the arch, loop, and whorl classification • Used for more precise identification

  12. Types of Points

  13. Using Minutiae Poinnts • Compare prints of the same finger and classification • One print may have as many as 100 minutiae points • No two fingers have the same pattern

  14. http://shs.westport.k12.ct.us/forensics/04-fingerprints/handout.htmhttp://shs.westport.k12.ct.us/forensics/04-fingerprints/handout.htm

  15. Latent Prints • Fingerprints found on a surface that aren’t visible to the naked eye. • Flashlight, UV light, or laser used to find prints • Dusting procedure is most effective if prints are oily (50% of the time) • Must be done carefully to not destroy the prints

  16. http://criminaljustice.state.ny.us/ojis/history/fp_sys.htm • http://en.wikipedia.org/wiki/Henry_Classification_System

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