Chemical analysis of bullet holes and environmental impacts
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Date
2018
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UMT, Lhr
Abstract
In the past, there is little work done on chemical analysis of bullet holes. No work is revealed about microscopic detailed analysis of bullet hole on clothing materials. This study focuses on microscopic and chemical analysis of bullet holes on the clothing material. The holes were produced by using 9 mm caliber ammunition having round nose bullet configuration. The holes were analyzed microscopically and chemically by two different colorimetric spot tests.
The sodium rhodizonate test which involves the direct spraying of sodium rhodizonate solution over the area having the bullet hole followed by the treatment with the buffer solution produces pink coloration. At last, followed by treatment with the HCl solution that indicates violet coloration corresponding to the presence of traces of Pb metal residues at the margins of the bullet. The dithiooxamide test involves the direct application of aqueous ammonia solution over the area having the bullet hole followed by the treatment with the dithiooxamide solution that indicates dark greenish grey coloration corresponding to the presence of traces of Cu metal residues at the margins of the bullet.The bullet holes were also analyzed microscopically for fine visual details. The microscopic examination reveals that margins of the bullet hole are split apart in irregular manner. Moreover, the periphery of the bullet hole fibers of the clothing material is transformed into spike shaped structure and bears a characteristic greyish to black bullet wipe. This is not observed in ordinary sharp tools made holes on clothing material.This microscopic and colorimetric analysis successfully establishes the identification of bullet hole consistent with the passage of the bullet. This method can be applied successfully to identify a bullet hole as a projectile entrance hole. Hence, it can differentiate between the bullet entrance and exit holes. This methodology makes it possible to differentiate that a sharp tool e.g. knife and firearm projectile made hole can be differentiated. This method can be applied successfully to eliminate a glowing cigarette burn hole on the clothing material. In future, such analysis can be performed on variety of materials such as polyethylene packing material, rubber surfaces, and plastic such as HDPE etc.