Geological Analysis of Soil and Anthropogenic Material. Three Case Studies

Abstract

In a judicial investigation, the evidence provided by pedological materials can have significant evidential value. The forensic geologist is able, in many instances, to obtain compatible results from pedological materials, and anthropogenic fragments in soil, by combining a variety of analytical methods. However, it must be noted that soil trace evidence can be modified during its transfer to an object, and after its deposition. This aspect needs to be considered when processing and interpreting the analytical data. In this paper, three cases are presented which exemplify the use of geological traces and anthropogenic materials in a criminal investigation.

The first case involves damage to a coachbuilder shop where soil samples contained unique anthropogenic fragments frequently used in the automobile industry and manufacturing. The presence of these in soil adhering on the suspects’ shoes compared well with the kind of work carried out in such workshops, and what was known about the nature of the crime. This allowed a link to be established between the footwear and the coachbuilder shop where the damage had taken place.

The second case is that of the homicide of a young girl: her burned body was found in the countryside near the town of Misilmeri, in Sicily. Soil found adhering to the roots of Cyperus alternifolius (umbrella papyrus) was found at the deposition site even though the plant was not growing there. This soil, and that found on the victim’s partially-burned shoes, was very similar to that attached to dried plants in the garden of the suspect’s home. The similarity of the soils, the presence of C. alternifolius at the suspect’s home, and the anomalous presence of the same plant at the deposition site, provided convincing evidence that the suspect had had contact with the place where the girl’s body was found.

The last case is the damage of Jewish graves in the Verano Monumental Cemetery in Rome. Tools belonging to a group of gardeners, who had been working illegally in the cemetery, showed traces of white material that could have been transferred from a damaged headstone during impact. Evidence from several independent analytical methods suggested that the gardeners had been involved in the offence.

These examples suggest how the data can be useful only if they are suitably placed in the context of the investigation. However, for better discrimination for studying soil samples in a judicial investigation, the analysis of the organic fraction of soil (e.g. botanical elements) is essential, especially in those cases where soil samples come from area with homogeneous pedology, or when it is necessary to distinguish the temporal deposition of a soil trace.