射击残留物的自动分析

Application and Techniques of Automatic Gunshot Residue Analysis

枪弹发射过程所形成的射击残留物(Gunshot residue,GSR)是枪击案件中一种重要的法庭物证,射击残留物分析的结果时枪击案件性质的判断、案件现场的重建、案件的侦查和法庭审判都具有重要的价值作用。目前扫描电镜能谱(SEM/EDS)法被认为是最具特异性的方法,利用SEM/EDS自动搜寻GSR颗粒软件的出现,则大大降低了劳动强度,提高了分析的准确性。因而受到了世界各国法庭实验室的青昧。然而,在我国由于一些技术上的原因,GSR颗粒自动分析软件在实际案件中应用得并不普遍,使得自动分析软件的优越性未能充分体现出来。目前商业化的GSR颗粒自动分析软件工作原理基本一致,均通过扫描电镜背散射图象的反差搜寻嫌疑射击残留物颗粒,并通过二次电子图象和能谱分析进行确认。本文从工作原理、样品制备、工作参数设定等方面详细介绍了其中一种GSR颗粒自动分析软件的应用,并根据作者多年的使用经验,对GSR颗粒自动分析的一些技巧进行了总结,供从事枪击案件物证检验的同行借鉴。

Gunshot residue （GSR） analysis is critical to scene investigation, scene reconstruction and court judgment in crime eases involved with gun. SEM/EDS method is thought as the most specific method to identify gunshot residue. The appearance of automated searching gunshot residue software based on SEM/EDS reduces labor to a great extent as well as keeping, high analysis accuracy, which make them popular in forensic laboratories in the world. But for some reason on techniques, automated SEM/EDS software for searching gunshot residue is not widely used in China, while their advantages have not been fully developed. The basic principle of all commercial automated GSR searching software is the same. That is to discriminate gunshot residue particles from other environmental ones by their BSD images, and to further confirm by their SE images and elemental components. The paper described the processes of automatic gunshot residue analysis by EDAX GSR software with its basic principle, sample preparation and setting of parameters etc. at first. Techniques on the application of the software were then presented in detail based on our experience in real casework.