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Explosives (From Scientific and Expert Evidence - Second Edition, P 587-617, 1981, Edward J Imwinkelried, ed. - See NCJ-88831)

NCJ Number
W D Washington; C R Midkiff
Date Published
31 pages
This study of explosives analysis considers types of explosives, evidence development, evidence packaging, and laboratory examination in explosive investigations.
Explosives can be classified according to their manufacture and intended use. Thus, they may be considered commercial, military, or improvised. These types can be further divided into low and high explosives based upon their burning rates. In the examination of uninitiated devices or those obtained in seizures or undercover purchases, the analytical approach used to identify the explosive is straightforward, which, in most cases, is the same as that used for postblast testing of initiated devices. After a bomb has been detonated, the investigator locates the crater or 'blast seat,' which provides a focal point for the bomb scene search. The crater will frequently contain explosive residues. Investigation then widens in circles from the crater. Special attention should be given to objects foreign to the crime scene, since these could have been parts of the explosive device. Proper packaging of the collected evidence for shipment to the laboratory is important. Containers should be close to the size of the evidence and be airtight to prevent loss of volatile explosive vapors and avoid cross-contamination of the exhibits. Laboratory examination consists of the identification of the explosive and other components of the destructive device. The explosive may be identified through vapor analysis, the presence of taggants that identify the manufacturer and the distributor of the explosive, microscopic examination, solvent extraction, infrared spectoscopy, thin-layer chromatography, gas-liquid chromatography, high performance liquid chromatography, spectrometric techniques, chemical spot tests, and combinations of tests. A glossary and 40 footnotes are provided.