NCJ Number
143866
Journal
Journal of Forensic Identification Volume: 43 Issue: 4 Dated: (July/August 1993) Pages: 362-367
Date Published
1993
Length
6 pages
Annotation
This article reports on two cases where coaxial lighting yielded a superior photographic fingerprint image compared to the image produced from the normal illumination techniques of transillumination and oblique lighting.
Abstract
Coaxial lighting uses a semitransparent mirror to observe dark details against a light background. In the case of fingerprints on a smooth, reflective surface, the light is diffused by the fingerprint deposit while being reflected specularly by the background surface. Coaxial illumination has been used in the past in conjunction with surfaces that are glossy and untreated or glossy and treated with cyanoacrylate esters. In the two cases described in this article, the advantages of such illumination were revealed in two other types of processing methods; vacuum metal deposition and crystal violet. Vacuum metal deposition was used to detect fingerprints on polyethylene bags containing heroin. Coaxial illumination yielded clearer fingerprint images than transmitted light. The second case involved the treating of the adhesive side of a tape with crystal violet. Compared to standard illumination, coaxial illumination eliminated the interference of an additional partial fingerprint. 5 figures and 6 references