NCJ Number
142372
Journal
Journal of Forensic Identification Volume: 40 Issue: 5 Dated: (September/October 1990) Pages: 271-278
Date Published
1990
Length
8 pages
Annotation
When luminol is applied to an area containing heme-like substances, a photoluminescent reaction causes the product to emit a faint but discernible light; because this reaction is temporary and not visible under normal light, the solution may be to use a film overlay negative system to show the luminol reaction in correct orientation with regard to crime scene objects.
Abstract
The film overlay negative system can be used to record a crime scene using ambient light or flash on one negative and then to record the luminol reaction in total darkness on a second negative. The separate negatives can then be combined when printed to create a single finished product. Required equipment includes a 35-mm camera with manual time/aperture settings, a tripod, and a cable release. By allowing evidence technicians a wider range of photographic opportunities when documenting the luminol reaction, the film overlay method can be used as an investigative aid and as a prosecutorial tool and can provide results that are judicially beneficial. Technical details on camera and darkroom operational steps are provided.