Geographical Information Science (GIS), spatial sampling and sediment variability examined using a case of manslaughter

The body of a missing person was found adjacent to a 3 km long sand-covered forest track in an upland area of Northern Ireland (UK). Geological trace evidence in the form of sand was found in the passenger footwell and on the foot pedals of a vehicle belonging to the last known associates of the deceased. A Geographical Information Science (GIS) methodology was used to integrate regional geological and soil databases to confirm the provenance of the sand and to find geographical locations for control (or alibi) samples. To complement the forensic examination in the case, 77 samples were taken at the scene in order to test whether such a collection assists knowledge of the scene, or whether fewer, targeted samples at access points to the body would have sufficed. The results demonstrate the potential applications of a GIS approach and show the usefulness of employing a spatial sampling scheme to understand the degree of local variability between samples. The findings from this study demonstrated that fewer samples would have been sufficient to associate the questioned items with the scene, yet would not have demonstrated how other areas of the track could be progressively excluded from comparison.