Methods Of Fingerprinting: Chris Strein

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  • 1. Methods of Fingerprinting Presentation by: Chris Strein
  • 2. Definition
    • A fingerprint is an impression of the friction ridges of all or any part of the finger.
  • 3. Types of Fingerprints
    • Latent
    • Patent
    • Plastic
  • 4. Latent Fingerprints
    • A fingerprint is any chance of accidental impression left by friction ridge skin on a surface, regardless of whether it is visible or invisible at the time of deposition
    • Electronic, chemical and physical processing techniques permit visualization of invisible latent print residue whether they are from natural secretions of the eccrine glands present on friction ridge skin (which produce palmar sweat, consisting primarily of water with various salts and organic compounds in solution), or whether the impression is in a contaminant such as motor oil, blood, paint, ink, etc.
  • 5. Patent Fingerprints
    • These are friction ridge impressions of unknown origins which are obvious to the human eye and are caused by a transfer of foreign material on the finger, onto a surface
  • 6. Plastic Fingerprints
    • A plastic print is a friction ridge impression from a finger or palm (or toe/foot) deposited in a material that retains the shape of the ridge detail
  • 7. Methods of Detection
    • Ninhydrin and Diazafluorenone
    • Vacuum Metal Deposition
    • Ethyl Cyanoacrylate Polymerisation
    • Adhesives
    • Argon Ion Lasers
  • 8. Ninhydrin and Diazafluorenone
    • Fingerprint reagents that are specific, for example Ninhydrin or Diazafluorenone react only with amino acids to show the fingerprint
  • 9. Various Chemical Methods
    • Ethyl cyanoacrylate polymerisation, work apparently by water based catalysis and polymer growth
    • Vacuum metal deposition using gold and zinc has been shown to be non-specific but detect fat layers as thin as one molecule
  • 10. How They Work
    • Natural secretions of the skin are deposited on a surface through fingertip contact
    • The resulting latent fingerprints consist usually of a substantial proportion of water with small traces of amino acids, chlorides, etc., mixed with a fatty, sebaceous component which contains a number of fatty acids, triglycerides, etc.
    • The method reacts with these substances and depending on what method it will illuminate or make the fingerprint visible due to the reaction with the specific element of the fingerprint
  • 11. Adhesives and Argon Ion Lasers
    • More mundane methods such as application of fine powders work by adhesion to sebaceous deposits and possibly aqueous deposits for fresh fingerprints that outline the print
    • Argon Ion lasers use a wide range of fluorescence techniques primarily for the enhancement of chemically developed fingerprints but also for some detection of inherent fluorescence of the latent fingerprints
  • 12. DNA Fingerprinting vs. Fingerprint Development
    • Fingerprint Development like the traditional methods just explained have a downside though. In fact, the chemical methods have multiple downsides. The chemistry of the fingerprint is destroyed or altered during the process of development and forensics have issues in obtaining the DNA of the fingerprint. Also, the methods rely on specific substances and sometimes are not effective based on the traces left.
  • 13. The Proposed Method
    • The method was developed at Penn State University and is being patented by professors Robert Shaler and Ahklesh Lakhtakia via provisional patent application for the process
    • “ The process is called conformal-evaporated-film-by-rotation, and was originally developed to create highly-detailed copies of biological surfaces such as insect eyes or butterfly wings. It utilizes a form of physical vapor deposition where materials are heated in a vacuum, causing them to vaporize and then condense on the surface of an object rotating above them, covering that object in a thin film.”
    • “ In the case of Penn State’s technique, the materials that they heated were magnesium flouride and chalcogenide glass, which is a combination of germanium, antimony and selenium. The film created was only about one micron thick, but that was enough to essentially “amplify” the ridges and valleys of fingerprints, allowing analysts to read them with an optical device.”
  • 14. Compare and Contrast
    • The process allows for the development of fingerprints and for physical analysis due to its translation of physical properties over the chemical properties and methods
    • Since it bases its analysis off of physical, not chemical, development, the chemistry of the fingerprint is left unscathed and forensic experts can then examine the fingerprints for DNA and receive more accuracy than with chemical methods
    • The only downfall is that the process is not portable; however, the professors and scientists are quickly at work in developing a portable version of the coating process and analysis
  • 15. In Conclusion
    • While the traditional methods using chemicals, lights, and x-rays are very effective at developing fingerprints, they can hinder the DNA and forensic processes in too many occasions that the Penn State professors developed a more practical and mutually benefiting method that will most likely replace the chemical methods due to their obsolete natures
  • 16. References
    • Sources:
    • http://www.gizmag.com/new-fingerprint-lifting-technique/15132/
    • http://www.upi.com/Science_News/2010/05/11/New-fingerprinting-technology-created/UPI-71761273609044/
    • http://news.oneindia.in/2010/05/12/newcoating-process-reveals-hard-to-developfingerprints.html
    • http://en.wikipedia.org/wiki/Fingerprint
    • http://www.sciencedaily.com/releases/2010/05/100511102121.htm
    • http://www.dnaindia.com/scitech/report_new-coating-process-reveals-hard-to-develop-fingerprints_1382162
    • Videos:
    • http://www.youtube.com/watch?v=HIck-I-S8r8
    • http://www.youtube.com/watch?v=cNw3e03rWa0