Institute of Forensic Medicine, University of Bern, Bühlstrasse 20, CH-3012, Bern, Switzerland.
Criminal Investigation Service of the Cantonal Police Department of Bern, Nordring 30, 3013, Bern, Switzerland.
Int J Legal Med. 2020 May;134(3):1115-1122. doi: 10.1007/s00414-020-02269-1. Epub 2020 Mar 4.
Shot range, the muzzle-target distance, is a crucial parameter for forensic reconstruction of deaths by firearms. In a large number of cases, especially suicides, the forensic pathologist is confronted with contact or near-contact shots, where muzzle gases play an additional role. This study was conducted to systematically investigate the influence of muzzle gases on the temporary cavity (TC). A total of 72 shots were fired using full metal-jacketed bullets in four forensically relevant calibres from 10-, 5-, 3-, 2- and 1-cm distance and in close contact. Target model was the so-called reference cube (10% gelatine at 4 °C) with 12-cm edge length. The TC was recorded using high-speed video (HSV). Cross-sectional analysis was performed by cutting the blocks to 1-cm slices, which were evaluated by applying the polygon method. The TC of shots from 10 and 5 cm distance had a tubular form. This aspect changed depending on the cartridge with decreasing distance (≤ 3 cm) into a pear-like form, which was typical for contact shots. The cumulated heights of the TC increased with decreasing distance below 3 cm. Contact shots approximately doubled the extension of the TC compared with exclusive energy transfer. Whereas HSV documented an increasingly asymmetric profile with ballooning at the entry side, cross-sectional analysis of cracks in gelatine resulted in convex graphs with only slight asymmetry for contact shots. Additional damage in gelatine was detected for 3-cm distance or less in calibre .357 Magnum and ≤ 2 cm for .32 auto, .38 special and 9mm Luger. The increasing influence of muzzle gas pressure is detectable with decreasing shot range below 3 cm.
射击范围，即枪口-目标距离，是枪支致死法医学重建的一个关键参数。在大量案件中，特别是自杀案件中，法医病理学家面临的是接触或近接触射击，枪口气体在此情况下发挥了额外的作用。本研究旨在系统地研究枪口气体对瞬时空腔（TC）的影响。总共使用全金属被甲弹在四个与法医学相关的口径（10、5、3、2 和 1 厘米）从 10、5、3、2 和 1 厘米距离以及近距离进行了 72 次射击。目标模型是所谓的参考立方块（4°C 时 10%明胶），边长为 12 厘米。使用高速视频（HSV）记录 TC。通过将块切割成 1 厘米的切片进行横截面分析，然后通过多边形方法进行评估。10 和 5 厘米距离射击的 TC 呈管状。随着距离的减小（≤3 厘米），这一方面会变成梨形，这是接触射击的典型特征。距离小于 3 厘米时，TC 的累积高度随着距离的减小而增加。与单纯的能量传递相比，接触射击使 TC 的扩展增加了大约一倍。尽管 HSV 记录到的入口侧膨胀的不对称轮廓不断增加，但明胶中裂缝的横截面分析仅导致接触射击的凸形图，且只有轻微的不对称性。在 3 厘米距离或更近距离的.357 马格南口径和≤2 厘米的.32 自动手枪、.38 特殊和 9 毫米鲁格口径下，发现了明胶中的额外损伤。随着距离小于 3 厘米，枪口气体压力的影响越来越大。
