MadSci Network: General Biology

Re: How are fingerprints detected at a crime scene?

Date: Wed Jul 5 23:38:44 2000
Posted By: Michael Doskotz, Grad student, Forensic Science - Toxicology, City University of New York
Area of science: General Biology
ID: 962816116.Gb

In the Book written by Dr. Peter DeForest, R. E. Gaensslen and Henry C. 
Lee Forensic Science, An Introduction to Criminalistics (McGraw-Hill Book 
Co. NY 1983) there are at least  nine different techniques for visualizing 
Latent Fingerprints.

1.)  Physical- Powder dusting
2.)  Oblique Lighting & Photography
3.)  Laser
4.)  X-ray
5.)  Chemical Iodine fuming
6.)  Ninhydrin
7.)  Silver nitrate
8.)  Fluorescamine, o-phthalaldehyde, dansyl chloride
9.)  Nitric acid, Hydrofluoric acid

  The choice of technique depends upon the type of surface that is being 
investigated.  For example on smooth, nonporous surfaces such as metal, 
glass, tile and finished woods the powder duting method can be used.  The 
powder (there are many types) will adhere to fingerprint residues 
(fingerprints are composed of water 98.5%, and solid material 1.5% = 
Lactic acid, fatty acids, Riboflavin, glucose, ammonia, peptides, Sodium 
  On paper Silver Nitrate can be the method of choice.

Good Luck in your work!

Mike Doskotz

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