NCJ Number
193725
Journal
Journal of Forensic Sciences Volume: 47 Issue: 1 Dated: January 2002 Pages: 44-51
Date Published
2002
Length
8 pages
Annotation
The detectability and stability of lachrymators (2-chloroacetophenone (CN), o-chlorobenzylidene malononitrile (CS) and synthetic capsaicin (nonivamide)) were investigated using dichloromethane extraction followed by gas chromatography-mass spectrometry (GC-MS).
Abstract
Criminal investigations of crimes sometimes involve the identification of tear gas sprays that have been used in crimes. It is usually impossible to identify the causative substances by on-site detection of air samples because of their low volatility. Instead, off-site detection of an on-site evidence sample is more realistic. In Japan, on-site evidence samples, such as spray containers, water, and wipe samples taken from the on-site surfaces with absorbent cotton, and victims’ samples such as clothes are collected and sent to forensic science laboratories. This paper tested the lachrymators CN, CS, and nonivamide (synthetic capsaicin). Lachrymators cause intense sensory irritation such as ocular erythema, local inflammation, and respiratory distress. Taking into account the real on-site evidence collected in offense odor incidents, the investigators selected “absorbant cotton” as wiped samples taken off the surfaces and “water” as the aqueous liquid, and reported the extraction efficiency of three lachrymators from these surfaces by solvent extraction followed by GC-MS analysis. Because tear gas is often sprayed in public places, the investigators selected “glass” surfaces representative of windows and victims’ spectacles, “stainless steel” for metals, and “absorbent cotton” for victims’ clothes. The investigation examined the stability of lachrymators on these materials and also the detectability of degradation products. The results showed that within a few days after spiking, CN could be detected from water or cotton, but not from the surface of glass or stainless steel. CS can be detected from cotton and wiped samples from the surface of glass and stainless steel, but not from water. Instead, degradation products of CS, o-chlorobenzaldehyde or o-chlorobenzoic acid can be detectable from water. Nonivamide, synthetic capsaicin can be detected from cotton, water and glass and stainless steel surfaces. Thus, for crimes in which tear gas sprays are used, the surfaces stained with tear gas should be collected as soon as possible, and the samples sent in closed containers to the forensic science laboratory. 30 References