Analysis of Gunshot Residues in Spent Cartridge Cases Collected from Shooting Incidents in Taiwan

• Main Authors: Fu-Kang Nai, 乃阜康
• Other Authors: Hsien-Hui Meng
• Format: Others
• Language: zh-TW
• Published: 1060
• Online Access: http://ndltd.ncl.edu.tw/handle/20110434110583876621

碩士 === 中央警察大學 === 鑑識科學研究所 === 105 === Scanning electron microscopy/energy dispersive X-ray spectrometry (SEM / EDS) is the standard method to detect inorganic gunshot residues, for domestic forensic science labortories. Spherical micro-particles composed of lead, antimony and barium are the targets of identification. However, with the popularity of lead-free and non-toxic ammunition, there are no lead, antimony and barium in the inorganic gunshot residues of these ammunition, so the criteria used to identify the inorganic gunshot residues should also be adjusted. In the guideline for the identification of inorganic gunshot residues of the E1588-17 issued by the American Society for Materials and Testing (ASTM) in 2017, analyzing the inorganic gunshot residues collected from gun barrels and spent cartridge cases is recommended. And the results are compared with suspicious samples to confirm whether inorganic gunshot residues are detected in suspicious sample. The spent cartridge cases from the scenes of shooting incidents occurred in Taiwan are collected. Inorganic gunshot residues samples are recovered from these cartridge cases and analyzed using SEM/EDS. The analyzed samples include all of the cartridge cases collected by local police forces in 2016, and part of the cartridge cases collected in 2014, 2015, and 2017. The results indicate that spherical micro-particles containing lead, antimony, and barium are detected in all spent arsenal-made cartridge cases. However, characteristic elements of GSR from lead free and non-toxic ammunition such as" gadolinium, titanium, zinc " and "gallium, copper, tin" are not detected in all arsenal-made cartridge cases. The less characteristic elements of GSR of non-toxic ammunition such as "titanium, zinc" and "strontium" are not detected in all arsenal made cartridge cases. The spherical micro-particles containing lead, antimony and barium; that are characteristic to inorganic GSR, are not detected in all spent homemade cartridge cases. Among the samples collected from spent homemade cartridge cases, the major detected element patterns are "phosphorus, chlorine, potassium, calcium" and "phosphorus, chlorine, potassium, calcium, sulfur". These results reveal that the possible sources of these elements are starting pistol caps and plastic disc caps. However, part of the inorganic GSR samples collected from spent homemade cartridge cases are found to contain lead and barium, or one of these two elements. According to domestic literatures these elements might come from the gunpowder of blank ammunition, or from the explosives of fireworks. We analyzed the inorganic gunshot residues collected from spent cartridge cases from shooting incidents in Taiwan, to acquine the information concerning the type of ammunition and the type of primers in the ammunition currently used by criminals in Taiwan. It is expected that the results of this study would provide helpful information for forensic science laboratories to interpret the results of GSR analysis in shooting incidents.