NCJ Number
219254
Journal
Journal of Forensic Sciences Volume: 52 Issue: 4 Dated: July 2007 Pages: 879-883
Date Published
July 2007
Length
5 pages
Annotation
This study tested whether combining the use of a dissecting microscope and an alternate light source (a Mini-Crimescope MCS-400 by SPEX Forensics) could improve the visibility of skin particles that might otherwise escape DNA analysis.
Abstract
The study found that the combination of a tunable light source and a dissecting microscope was helpful in identifying small skin particles, depending on the fluorescence characteristics of the carrier or contaminating material. When carrier materials and some impurities do not fluoresce, the use of the alternate light source and the filters can significantly improve the visibility and detection of skin particles. On the other hand, some carrier materials and some impurities can fluoresce as well. Soil components, fibers, and laundry detergents can emit fluorescence. In some cases this background fluorescence may mimic the appearance of the skin particle, so the application of the alternate light source is not helpful. The use of a fluorescent dye such as DFO (1,8-diazafluoren-9-one), which reacts with amino acids in skin, could help to boost skin fluorescence. An experienced practitioner is still necessary for the prevention of false-negative or false-positive conclusions. For the experiment, skin particles were hidden within four types of sand, fibers, and soil samples. Skin particles were also placed on various surfaces such as textiles, stones, wooden shafts, and metals. The visibility on the exhibits was compared under natural light and with the alternate light source. The Mini-Crimescope MCS-400 provides 16 different excitations that range from 300 to 670 nm. The illuminant is a 400 W DAYMAX metal halide lamp with a ceramic reflector, which has a larger light intensity than a 500 W Xenon bulb. A filter is required to screen out any reflected incident or competing light. 1 table. 6 figures, and 18 references