(FPT) Fingerprints Module Overview

Fingerprints Module Overview 

Fingerprints are very unique; the odds of having the exact same fingerprints as another person are about 1 in 10 billion on a planet with a population of roughly 7 billion people. Fingerprints are actually formed in the womb by the amniotic fluid swirling around the fingers of the fetus as they touch surrounding structures and are fully formed by the 17th week of pregnancy! Because of this fascinating and individual development process, fingerprints are very valuable evidence in a Forensic investigation. While identical twins may have the same DNA, they can always be differentiated by their fingerprints. A suspect may not see their fingerprints on a surface, but Forensic Investigators have several ways to make even the most elusive fingerprints reveal themselves!

Essential Questions

    1. Why are fingerprints unique to each individual?
    2. How are fingerprints classified and stored in AFIS?
    3. How are fingerprints collected and stored?

Key Terms

  1. IAFIS - Integrated Automated Fingerprint Identification System is a computer database system that scans fingerprints from crime scenes and compares them with millions of others around the world. The database also includes criminal histories, physical descriptions, photos and other information.
  2. Minutiae - Also known as ridge characteristics, minutiae are major features of a fingerprint, of which comparisons of one print with another can be made. Some minutiae found in fingerprints include bifurcation, core, delta, or island. Minutiae make fingerprints unique to the individual and are thus individual evidence.
  3. Loop - Type of fingerprint patter in which it must have one or more ridges that enter from one side of the print, re-curve, and exit from the same side. It only has one delta.
  4. Arch - Type of fingerprint pattern formed by ridges entering from one side of the print, rising in the center and exiting on the opposite side. It has no core or delta.
  5. Whorl - Type of fingerprint pattern containing one or more cores and a minimum of two deltas.
  6. Latent Print - Impressions caused by the transfer of body perspiration or oils present on the finger to the surface of an object. Visible and plastic prints may simply be photographed and/or preserved with the object on which they are left. Latent prints, however, must be located and developed.
  7. Plastic Print - Ridge impressions left on a soft material such as putty, wax, soap, or dust.
  8. Patent Print - Prints made by fingers, palms or feet touching a surface after they have been in contact with colored material, such as blood, paint, grease, or ink. These are also known as visible prints.
  9. Dactylography - The scientific study of fingerprints as a means of identification.
  10. Core - The approximate center area of a fingerprint. Some fingerprints have more than one core depending on the pattern (such as whorl).
  11. Eccrine Glands - Sweat glands located mainly in the palms of the hands and soles of the feet. They secrete a liquid that is 99% water and 1% chlorides, metal ions and amino acids.
  12. Apocrine Glands - Found in hair follicles, apocrine glands secrete cytoplasm and nuclear materials, including inorganic compounds, such as ionic iron, and organic compounds such as proteins, carbohydrates and cholesterol.
  13. Sebaceous Glands - Found in places where hair grows secretors of fatty or greasy substances. These include organic compounds, such as fatty acids and glycerides, as well as alcohols and hydrocarbons.
  14. Dermal Papillae - In the human skin, the dermal papillae are small, hills of dermis that project into into the epidermis. At the surface of the skin in hands and feet, they appear as epidermal or papillary ridges (colloquially known as fingerprints).
  15. Iodine Fuming - Iodine crystals are heated and through sublimation turn from solid to vapor (gas) without entering into a liquid phase. The vapor then adheres to the fingerprint and makes it visible in a characteristic brown colored print.
  16. Ninhydrin - A chemical that reacts with amino acids to form a purple compound. This development technique is used primarily on porous surfaces, such as paper, tissue, and clothing.
  17. Silver Nitrate - When exposed to ultraviolet (UV) light, silver nitrate reacts with the salt in sweat to form a black/brown compound. This type of fingerprint development is best used on porous surfaces, like paper or drywall.
  18. Cyanoacrylate - Superglue that is used as a forensic tool to capture latent fingerprints on non-porous surfaces, like glass and plastic. Cyanoacrylate is warmed to produce fumes that react with the invisible fingerprint residues and atmospheric moisture to form a white polymer (polycyanoacrylate) on the fingerprint ridges. The ridges can then be recorded. The developed fingerprints are, on most surfaces (except on white plastic or similar), visible to the naked eye.

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