Trace evidence examination using laboratory and synchrotron X-ray diffraction techniques

Abstract

AbstractIn a 2007 homicide in Western Australia, small (<0.5 mm diameter) red brick fragments and soil were identified on the victim's clothing (mainly bra), body (mainly hair) and vehicle. A comparative study of the mineralogy and morphology of the red brick fragments with red bricks from the paved area in front of the victim's house was undertaken by traditional laboratory X-ray diffraction (XRD) using low background Si wafer holders and a 0.5 mm focusing monocapillary attachment. Whilst significant similarities were observed between the two datasets, peak overlaps and poor resolution prevented a specific provenance to be determined. Additional analyses using the superior intensity and resolution of synchrotron XRD that was conducted at the Australian Synchrotron quantified the mineralogy of polycrystalline minerals (cristobalite and mullite) in the small brick fragments. These data established that the brick fragments could not be distinguished from the driveway bricks and were clearly shown to be different to a range of other possible sources.The trial was before a judge only and he concluded that the mineralogy data from the small brick fragments on the victim's clothing and the bricks from her front driveway indicated that she was initially attacked in her front yard and not at Kings Park where her body was buried.