X-Ray Spectrometry in Forensics

X-ray techniques are widely used by forensic laboratories, e.g., for the analysis of fibres, hair, glass and paint specimens. Advantages of the technique are its low cost, non-destructive nature, ease of operation and interpretation.
Melanie Bailey, University of Surrey, Guildford, UK, edited a special issue comprising a collection of articles focusing on how complementary X-ray spectrometry methods may assist the forensic investigations of the future.

For example, Anna Galli, CNR-IFN, CNR – Istituto di Fotonica e Nanotecnologie, Milano, Italy, and colleagues show how portable energy-dispersive X-ray fluorescence (XRF) devices are used in cultural heritage. Forensic and cultural heritage scientific analyses have several similarities. Both deal with unique, ‘precious’ and often quantitatively very limited objects, which have to be preserved as much as possible. The team shows a few peculiar case studies in which scientific examination proved to be helpful in solving historical and archaeological uncertainty.

One of the most important aspects of the criminal investigation of a shooting incident is the target-to-muzzle distance determination. This can establish the relative positions of the shooter and the victim or even help to establish the shooters’ intent. Joao F. Fonseca, Laboratório de Polícia Científica da Polícia Judiciária, Lisbon, and Universidade de Lisboa, Lisbon, both Portugal, and colleagues demonstrate that energy-dispersive XRF can be an alternative for the standard procedure using chemographic tests. Big advantages are that it is fast, non-destructive, and without the need of chemical preparation.

Jun Kawai, Kyoto University, Japan, gives an interesting account of the Jury’s interpretation of the synchrotron XRF (SXRF) data from two experts to analyze a poisoning case by arsenic in 1998 in Japan. By adding his own interpretation to the data, he highlights the complexity of interpretation of XRS spectra in a forensic context. Recent analysis of Fe, Zn, Mo, and Ba in one of the raw spectra measured in 1998 reveals the arsenic stored in the kitchen of the condemned criminal in the death row was significantly different from that of the paper cup used for poisoning.