Combined effort singles out murder weapon

Combining results from inductively coupled plasma atomic emission spectrometry (ICP-AES) and scanning electron microscope-energy disperse X-ray microanalysis (SEM/EDX) could soon be used by forensics experts to discriminate between metallic implements that have injured or killed a person. Such technology would be especially useful where an unambiguous identification of the weapon based on entry wound examination is not possible.

Rufeng Bai of the Department of Forensic Science, at the Medical College of Shantou University, Lihua Wan of the Department of Laboratory Medicine, at Chongqing University of Medical Science, and Hongwei Li, Zhong Zhang, and Zhihua Ma of the Institute of Chongqing Criminal Science and Technology, PR China point out that forensic testimony regarding a murder weapon is among the most important evidence and chemical analysis of the weapon in question should provide "excellent results".

The researchers examined metal particles in five wounds made in the skin of domestic pigs, respectively, using Cu-Zn or Cr-Ni coated and carbon steel kitchen implements using EDX. They used ICP-AES to determine particulates resulting from carbon-steel kitchen implements and compared the readings obtained from wound samples with the blades. Previous studies with these two techniques used separately demonstrated that they may not consistently provide definitive results.

Residues from samples where a coated implement had been used revealed only the expected elements Cu, Zn or Cr, Ni. However, the carbon-steel wounds revealed Fe, Cr, Si or Fe, Mn, Si. The team points out that EDX can be used to examine particles in wounds and to deduce the category of a metal injury implement, but used in conjunction with ICP-AES it can allow different implements of the same type to be distinguished.

In a peculiar twist of the knife, the research paper was appeared on Valentine's Day, a day infamous for its associations with murder and massacre.