Comparison of Fingermark Detection Using Semiconductor Laser and LED Light Sources with Three Chemical Reagents - Technology Evaluation

• NCJ Number: 237795
• Date Published: May 2010
• Author(s): National Forensic Science Technology Center
• Agencies: NIJ-Sponsored
• Award: Forensic Technology Center of Excellence

Annotation

This study was conducted to determine the optimum light and filter combinations of laser and light-emitting diode (LED) light for use with indanedione and two new chemical reagents, genipin and lawsone, in detecting and identifying latent fingermarks.

Abstract

The findings show that treatment with indanedione zinc chloride was most effective in the excitation of fingermarks. With the exception of the 577nm laser and genipin, the two new reagents, genipin and lawsone, did not provide useful results under test conditions. Although the LED light source revealed a significant number of untreated impressions, the laser light source proved to be more sensitive at detecting untreated impressions, and the ridge clarity was often higher on the samples examined. Monochromatic sources (lasers) and broad-band sources such as LEDs each exhibited the potential to detect evidence missed by the other. The light sources used were Coherent TracER lasers operating at 460nm, 532nm, and 577nm; and the Rofin Polilight Flare Plus LED operating at 505nm. Deliberate and randomly created fingermarks were first examined using the light sources alone and then again following treatment with one of the reagents. Figures, table, and references