NCJ Number
191318
Journal
Journal of Forensic Sciences Volume: 46 Issue: 5 Dated: September 2001 Pages: 1085-1092
Date Published
September 2001
Length
8 pages
Annotation
This paper examined how latent fingerprints deposited on metallic surfaces might be visualized directly, without development or any other form of perturbation, by Volta potential mapping using a scanning Kelvin microprobe.
Abstract
In the past, numerous methods had been described for the development of latent fingerprints on metal surfaces. However, electrochemical interactions between latent human fingerprints and metal surfaces in ambient air were investigated using a scanning Kelvin microprobe. Inorganic salts present in sweat deposited at fingerprint ridges locally depassivate the metal surface producing a Volta potential decrease of greater than 200 mV. The Volta patterns may persist for months and prints may be visualized by potential mapping. Because the Volta potential differences were produced by involatile salts, they persist when the organic components of the fingerprint residue were volatilized by heating to 600 degrees Celsius. Graphs and references