ABSTRACT:ObjectiveTo estimate the shooting distance of model 64 pistol by visualizing the patterns of nitrous compound in gunshot residues (GSRs) using modiifed Griess test (MGT).MethodsA series of GSR samples by shooting against a target of PU cloth (30 cm×20 cm) at muzzle-to-target distances of 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 80, 100, 120, 140, 170, 200, 300, 500 and 1000 cm were analyzed. A new device had been made, so that the shooting samples could react with photographic paper treated with modiifed Griess reagent in acetic vapor. The orange spots in photos exhibited the location of gunshot residue containing nitrite, and stood for the distribution of nitrites. The coloring process was optimized on such aspects of reaction device, reacting temperature, reacting time and photographic paper. The test was carried out as following:ifrst, the reacting tray with 30% acetum was heated to 80℃ for 3 min, then a piece of printing photographic paper was treated with modiifed Griess reagent for 1 min, dried for 1 min, and was reserved between two printing papers. The reaction took place for 5 min with the stack on coloring plate which had the iflter paper with the gunshot sample, the processed photographic paper, the gauze, the sponge on top; lastly, took picture of the reacted photographic paper. The chroma at -30 and saturation at 70 were set in Photoshop.ResultsA photo-bank of color spot distribution related to shooting distance was built up from this gunshot sample collected at distances within 0~1000 cm. The images of 0, 2 and 5 cm samples were brielfy color lumped and the color lump area increased with the distance. Above 2 cm, the radius of color lump distribution increased distinctly, and the color spots exhibited the trend of denseness to thinness. The samples within 100 cm revealed the discriminating color spot distribution with each other while the color spot differences were inconspicuous over 100 cm distance. There were almost no color spots visible beyond the distance of 200 cm.ConclusionsThe color spots developed with the method are deifnite, stable and repeatable. Using this approach, it is possible to accurately estimate the ifring distance from the target.%目的：利用改良格里斯熏显法测定64式手枪射击残留物中亚硝酸根的分布推断射击距离。方法对格氏试剂显现射击样本中亚硝酸化合物的显色装置、显色温度、显色时间、显色相纸、色斑处理等条件进行优化，分析了系列距离（0、2、5、10、15、20、25、30、35、40、45、50、60、80、100、120、140、170、200、300、500、1000 cm）PU射击样本，建立色斑分布随距离变化图片库。结果0、2、5 cm样品以色块为主，0 cm样本有与撕裂纹相应的橙色线条，色块随距离增大呈增大趋势；从2 cm开始，斑点分布范围随距离增大而明显增大，斑点由多而密向少而疏的趋势发展；100 cm内不同距离射击样本显色结果差别明显；100~200 cm射击样本显色斑点差异减少；200 cm外射击样本难以发现斑点。结论本法显现的色斑不扩散，清晰度高，稳定性好，相同射击距离色斑分布形态基本一致。比较检材及同质射击样本色斑分布的异同可推断射击距离。
展开▼
