NCJ Number
118084
Journal
Journal of Forensic Identification Volume: 39 Issue: 3 Dated: (May/June 1989) Pages: 177-180
Date Published
1989
Length
4 pages
Annotation
Laser detection of fingerprints is an effective technique to discover traces of contact between person and object in criminal investigations.
Abstract
By visualizing prints that might not otherwise be located, the laser can be used to isolate a print from an otherwise competing or obscuring background. When prints appear on a sharply curved surface, such as a gun barrel or small diameter pipe, they are sometimes difficult to visualize with regular photography. By virtue of its ability to enhance contrast, the laser can be used to great benefit. After processing with vapor phase cyanoacrylate ester, fluorescent dyes can be applied to the cyanoacrylate print in liquid, vapor, or powder form. When examined under a blue-green laser, these dyes fluoresce. The fluorescing latent print is photographed by 'painting' it with laser or ultraviolet light. Because laser output is a collated beam, broad diffuse illumination is not possible; the beam will not be able to light all sides of the curved surface simultaneously. This technique is accomplished by moving the laser light from one side of the latent print on the curved surface to the other side slowly during film exposure. Enhancement of the latent print by laser-excited luminescence can somewhat eliminate background so that ridge details will have more contrast. 7 figures, 9 references.