تسجيل الدخول

تسجيل

Visual Examination

المؤلف:  Max M. Houck، Jay A. Siegel

المصدر:  Fundamentals of Forensic Science

الجزء والصفحة:  485

2026-08-22

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Visual Examination

In order to analyze explosive residues, they must be isolated from the matrix in which they are found at the crime scene. The best way to do this is by manually removing them under a low power microscope. This is often a tedious and time-consuming activity but can pay dividends later. Isolated residues can be more easily characterized without having to be concerned about the presence of impurities. More importantly, the forensic scientist can testify that actual particles of explosive were recovered from the debris and were chemically identified. If no large particles of undetonated explosive can be isolated, then it may be necessary to dissolve microscopic particles with a suitable sol vent and remove them from the debris. This is a lot faster than manual sifting but suffers from several disadvantages. First, other substances may also dissolve so the explosive residue is not really being purified. Second, many explosives have components that are ionic, such as potassium nitrate; KNO3. When this material is dissolved, it dissociates into potassium and nitrate ions. The resulting analysis indicates that the ions were pres ent but not the actual compound. One could argue that these ions could have arisen from any of a number of sources and this doesn’t prove that an explosive is present.