NCJ Number
213741
Journal
Journal of Forensic Sciences Volume: 51 Issue: 2 Dated: March 2006 Pages: 296-302
Date Published
March 2006
Length
7 pages
Annotation
This paper describes the basic methodology of pyrotechnic reaction residue particle analysis (PRRP), which involves determining whether the scene of an event under investigation contains a mixture of chemical elements and compounds that is capable of a self-contained and self-sustained exothermic chemical reaction for the production of heat, light, gas, smoke, or sound (a pyrotechnic reaction).
Abstract
The paper first provides background information on the similarities between PRRP and primer gunshot residues (PGSR) and their analysis. Important differences between PRRP and PGSR are also noted, which potentially makes performing PRRP analysis more difficult than PGSR analysis. In both types of analysis the preferred method is to use scanning electron microscopy to locate suspect particles, followed by the use of energy dispersive x-ray spectroscopy to identify the particle's chemical elements. There will be few occasions when standard micro-analytical chemistry performed on pyrotechnic residues will not provide sufficient information to enable forensic investigators to determine whether or not a pyrotechnic event occurred at a particular scene; however, when more information is required to determine what happened, PRRP analysis provides an improved ability to distinguish between materials produced by a pyrotechnic reaction and other unrelated substances also present. The greater specificity of PRRP analysis results from its ability to identify individually a large number of micron-sized particles, compared with the ability of standard micro-analytical chemistry to produce only a single integrated result. After describing basic PRRP methodology, this paper explains how PRRP analysis was used in a particular investigation to distinguish between pyrotechnic residues and unrelated background contamination; to determine that two different pyrotechnic compositions had previously exploded within the same device; and to establish the chronology of an incident that involved two separate explosions that occurred close together in time. 8 figures, 1 table, and 9 references