Potential and Pitfalls in Establishing the Provenance of Earth-Related Samples in Forensic Investigations

• NCJ Number: 215149
• Journal: Journal of Forensic Sciences Volume: 51 Issue: 4 Dated: July 2006 Pages: 832-845
• Author(s): Barry G. Rawlins Ph.D.; Simon J. Kemp B.Sc.; Emily H. Hodgkinson Ph.D.; James B. Riding D.Sc.; Christopher H. Vane Ph.D.; Catherine Poulton M.Sc.; Katy Freeborough B.Sc.
• Date Published: July 2006
• Length: 14 pages
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America

Annotation

This study tested the independent and collective opinions of four experts regarding the sources of soil and plant samples from various environments unknown to the experts.

Abstract

Independent interpretations of each of the experts based on one technique of analysis were less accurate than collective interpretations based on combined findings from all four of the tests used by the experts. Findings from collective, consensual judgments of the experts were accurate in determining two of the three source sites of soils where the mineralogy and plant communities were distinctive. Although the mineralogical analysis correctly identified the Triassic mudstone soil parent material at the other site, carboniferous spores from domestic coal were mistakenly interpreted as coming directly from bedrock. Such an interpretation could be a common pitfall due to the human redistribution of material such as coal. Overall, the study shows that combining four techniques in identifying soil minerals and local plant communities is effective in providing information on the source environment of plant and soil material when source sites have distinctive mineralogical or vegetative properties. The authors note that real-life forensic sample-to-source matches are less "blind" than the experiment, in that they usually involve matching a sample found on a suspect to the natural environment of a known crime scene. Before their examination of the soil samples, the four experts were only told that each sample had been collected from a unique site on the mainland of England. Each expert's opinion about the site source for each of the three samples was first determined. The experts' collective interpretation was then determined. The identification methods used were X-ray diffraction, scanning electron microscopy, the assessment of pollen assemblages, and structural characteristics of organic matter at the molecular level. 4 tables, 10 figures, and 52 references