APPLICATION OF NUCLEAR AND ALLIED TECHNIQUES FOR THE CHARACTERIZATION OF FORENSIC SAMPLES

摘要

Forensic science deals with the application of various techniques - physical, chemical, and biological - for crime investigation. The legal implications of such analyses put considerable restrictions on the choice of techniques. Moreover, the unknown nature of materials, the limited availability of samples, and the large number of elements to be analysed put considerable strain on the analyst to select appropriate methods. The availability of nuclear techniques has considerably enhanced the scope of forensic analysis. Multi-technique approaches, involving nuclear and non-nuclear analytical methods, have proven to be valid and versatile. In this paper we present recent results from the use of nuclear and allied analytical methods for forensic applications. Some of the forensic samples recently analysed in our laboratories will also be discussed. One of the major types of samples handled pertains to the identification of gunshot residues, and nuclear techniques have considerably simplified interpretation of results. Analysis of unknown materials like powders or metallic fragments for the possible presence of illicit nuclear material is becoming more essential. Characterization of materials is also of importance in view of the possible dumping of toxic wastes from developed countries in developing countries. Detection of gold in a smuggling case was possible using X ray fluorescence and neutron activation analysis even though the smuggler used an innovative approach and converted the gold to a colourless cyanide complex to prevent its easy detection. Analysis of commercial pharmaceutical or medicinal preparations for toxic metals is also becoming important in view of the illegal use of materials like heroin. The increasing volume of illegal and criminal activities requires judicious application of nuclear and non-nuclear techniques for the conviction of criminals and, more importantly, for acquittal of the innocent.