骨骼上工具痕迹预处理新方法研究

A New Pretreatment Method for Toolmarks on Bone

针对骨骼上的工具痕迹,研究一种既能增强工具痕迹特征又有利于物证长期保存的预处理方法。选择猪的棒状骨骼为实验材料,模拟现场骨骼上的工具痕迹形成条件,锯割棒状骨骼制作痕迹样本;研究不同种类有机溶剂的处理效果,以及处理步骤、处理时间对脱脂脱水率及工具痕迹特征的影响。选定乙醇石油醚作为骨骼预处理方法的有机溶剂,确定预处理步骤为超声波清洗、乙醇脱水、石油醚脱脂及红外干燥,确定乙醇浸泡时间为300 min、石油醚浸泡时间为300 min、红外干燥时间为120 min。本文建立的基于乙醇石油醚及红外干燥的预处理方法对骨骼上的工具痕迹特征无影响,且可增加痕迹的反差,利于痕迹特征的观察及拍照提取,处理后的骨骼经长时间保存不产生刺激性气味,便于物证保管。

Toolmark on bone was selected as research object and a new pretreatment method on defatting bone was developed in this paper. The study aims to enhance the characteristics of toolmarks on bone and extend the storage time of similar evidence. The pig claviform bone was selected as the experimental material to generate the tested tool marks. A total of 30 samples were made by the pig bones being sawn with a steel saw and real conditions simulated for toolmarks in crime scene. The influences of different types of organic solvent, steps of defatting and time of treatment on features of toolmarks on bone and defatting ratio were analyzed with simulating experiments in laboratory. The organic solvent, steps of defatting and treatment time were optimized, and a new and effective pretreatment method for defatting bone by absolute alcohol, petroleum benzin and infrared drying was developed. Instead of destroying the features of toolmarks, the method could enhance the contrast of striation present on fracture surface of bone, convenient for further recovering and examining toolmarks on bone by photography. Meanwhile, no pungent smell was produced from a defatted bone after long storage in glassware. This paper presents a new pretreatment technique of defatting bone to safeguard further toolmark determination and storage of evidence.