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Fingerprints

Fingerprints. Chapter 14. History of Fingerprinting. First used by Chinese to sign documents (3000 yrs. Ago Henry Fauld first published paper describing use of fingerprints for identification ; 1880 suggested these ridges could be used to identify criminals

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Fingerprints

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  1. Fingerprints Chapter 14

  2. History of Fingerprinting First used by Chinese to sign documents (3000 yrs. Ago Henry Fauld first published paper describing use of fingerprints for identification ; 1880 suggested these ridges could be used to identify criminals Francis Galton—published book about fingerprinting in 1892 that led increase in use of fingerprinting Sir Richard Henry—came up with classification system for fingerprints Began in US in 1901 in New York City 1924—FBI started fingerprint records for matching suspects

  3. Introduction of Fingerprints—Fundamental Principle 1 Fingerprints are one of a kind entities Fingerprint individuality occurs in the ridge characteristics or minutiae The minutiae are ridge endings, bifurcations, enclosures, and other details

  4. Fingerprint Ridge Characteristics—Makes 100% original Bifurcation—indentation Ridge Ending—End of line Ridge—Upraised line Enclosure—line closes off a space Ridge Island—small dot

  5. Fingerprints: Fundamental Principle 2 They are unchanged during one’s lifetime Also found on palms and soles of feet; designed to give some friction to avoid slippage from surfaces Oils and sweat prints make invisible latent prints on surfaces

  6. Fingerprints: Fundamental Principle 3 Have common patterns that allow for classification Loop—ridge lines that enter from one side of the pattern and exit at same side Whorl—ridge patterns that are rounded or circular and have two deltas; plain whorl, central pocket loop, double loop, and accidental Arch—ridge lines enter pattern from one side and exit from the other; plain and tented http://www.youtube.com/watch?v=Ry8920R7bxs&feature=related

  7. Fingerprint Classification First level—assigns a fraction number Presence of absence of whorl pattern gives determination If a whorl is present on pair #1, 16 on pair #2, 8, on pair #3, 4, on pair #4, 2 and on pair #1 1 Zeros are put in when there aren’t any whorls in pairs Pair 1 is Right index/Right Thumb, Pair 2 is R Ring/R Middle, Pair 3 is L Thumb, R Little, Pair 4 is L Middle/L Index, Pair 5 is L Little/L Ring

  8. Automated FingerPrint ID system (AFIS) Print ridge are now matched to prints in system Livescan takes inkless digital prints and compares them to AFIS database Speedy and accurate AFIS gives list of potential prints and then a trained analyst will make decision if prints match the tested ones http://www.youtube.com/watch?v=ZKi1CKTRCQM&feature=related

  9. Fingerprints Visible print—left in dink, dirt, blood, something visible Plastic print—impression in soft surface like dirt, clay, etc. Latent prints—invisible due to oil and sweat deposits on surface Visible and plastic prints are easily detected Latent prints are not as easily detected Reflected Ultraviolet Imaging System (RUVIS) use ultraviolet imagery to locate latent prints

  10. Developing Latent Prints--Powders Fingerprint powders—applied with camel hair brush and adhere to oils and perspiration; usually gray and black and selected to contrast background color Magnetic sensitive powders—uses magnetic brush to dust prints; no contact damage Fluorescent powders-fluoresce under UV light

  11. Developing Prints—Iodine and Ninhydrin Iodine fuming—visualize prints by exposing to iodine Iodine sublimes to gas from solid and make print visible Ninhydrin—chemical used to develop latent prints on porous materials by reacting with amino acids in sweat; mixed with solvent like acetone or ethyl alcohol and sprayed on surface; can take 1 to 48 hours

  12. Other methods for developing Prints Physical developer—silver nitrate reagent used to develop latent prints on porous surfaces Super glue fuming—exposes latent prints on nonporous surfaces to cyanoacrylate vapors; named for super glue; can be done on site Laser light—perspiration fluoresces with laser light http://www.youtube.com/watch?v=NjGyil6k75M&feature=fvw

  13. Preservation of Prints After analysis, prints must be preserved for the courts Photographs of print and location of print at crime scene Take entire item with print as evidence (if small enough) From large immovable objects, prints must be lifted by adhesive tape (like scotch tape) Digital imaging—prints are converted to digital image and can be enhanced for the most accurate analysis Digital images can be put into print database Allows analysis of just portion of print

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