Abstract Soil science and geology are specialist disciplines that can make a valuable contribution to forensic science investigations. Despite a resurgence in earth material examination associated with criminal investigations, its full potential has probably not been realized. This paper discusses some of the issues that impact on the effective participation of soil science and geology in a broad forensic science context and why it is important for meaningful partnerships between forensic science service providers and specialist soil science and geology institutions to be established.

Abstract 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.

Abstract Soil examination can provide useful forensic information about the spatial location and human activities of a suspect. Soil is widely used in criminal investigations. In a case that occurred in the countryside of Jilin Province, in the NE of China, soil was found adhering to clothing on a body. Examination of plant debris in the soil using plant DNA barcoding technique found it to be ginseng root, which indicated that the soil might have come from a ginseng plantation. In the first instance, it helped in finding the place where the body was initially buried. Then a comparison was made between the soil recovered from the body and from the ginseng plantation. Composite analysis of minerals, pollen types and elements provided additional information to assist in making comparisons. Trace amounts of soil located on the body played an important role in locating the burial site and was regarded as the most valuable evidence in convicting the suspect of murder even without the suspect's DNA being available.

Abstract In a cold case investigation of a 1983 homicide, trace amounts of soil were identified on a 10-year-old victim's pyjama top. Swatch samples were cut from the pyjama top, specifically the hem, to determine the provenance of this questioned soil. A comparative study was undertaken of the questioned soil with control soils from the Onkaparinga estuary using morphological observations with the naked eye and scanning electron microscopy (SEM), chemistry, traditional laboratory X-ray diffraction (XRD) and synchrotron µ-XRD. Synchrotron µ-XRD with high-intensity X-rays provided greater sensitivity and resolution than the laboratory XRD source to identify pyrite and clay minerals on the pyjama top. SEM confirmed that these mineral particles are deeply impregnated in gaps between fibres of the fabric, which are likely to have originated under water with force being applied on the pyjama top – implying that the victim was pushed into the mud. This is substantiated by transference shaking experiments, where mineral particles are dominantly located on the surface of the fabric. The questioned soil samples have a moderately strong degree of comparability with the control hypersulphidic subaqueous soils containing pyrite in the Onkaparinga River estuary – providing evidence that the soils have similar origins. The accused was found guilty by a Supreme Court judge of murder.

Abstract Unsolved crimes add significant financial, legal and social costs to the community. Therefore, there is an urgent need to develop robust solutions to deal with this growing issue. Soil forensic analysis is an emerging cross-disciplinary science that can deliver powerful physical evidence with significant benefits to criminal, counter-terrorism and environmental crime investigations. Technologies currently used, which are largely dependent on the examination of inorganic soil components, are unable to successfully resolve approximately 20% of soil comparisons in cases due to a deficiency in spatial resolution. The organic component of soil includes a vast number of living organisms, and the combination of these organisms can provide a biological signature to assist with soil comparisons. Recent developments in DNA sequencing technology enable characterization, and comparison, of these complex soil communities, providing additional discriminatory information that could potentially assist in cases that cannot currently be resolved. DNA analysis is routinely applied in forensic science to answer human- and non-human-related questions. This paper provides a broad overview of forensic DNA analysis, and describes the differences between DNA analysis of single specimen and complex soil DNA mixtures. We also highlight key areas of future research required for this technique to be fully utilized in casework.

Abstract Soil material found on questioned items (such as footwear, tools or vehicles) during a police enquiry can provide powerful forensic intelligence (and evidence) relating to geographical origin. We evaluated the potential of organic biomarkers (i.e. plant wax compounds n -alkanes and fatty alcohols) and microbial community DNA profiles (bacterial and fungal) in providing land-use-based intelligence within two geographically separated urban study areas. Our results demonstrate the limited potential of basic soil physico-chemical analysis, mineralogy (X-ray diffraction) and spectroscopic (colour and Fourier transform infrared) methods in providing land-use intelligence within these specific localized urban environments. Our results also demonstrate the complementary nature of biochemical/biological analysis to mineralogy, providing important information about the variability of analysis in localized urban environments. However the n -alkane compounds proved variable within land-use types. Bacterial DNA profiles were influenced by both land use and the urban/geographical origin. Fatty alcohol compounds and fungal DNA profiles provided characteristic analyses that discriminated grass-dominated, flowerbed, woodland and roadside soils, regardless of urban/geographic origin. Supported by appropriate knowledge of landscape variability (e.g. spatial, temporal), these methods demonstrate potential to provide rapid and cost-effective land-use-based intelligence to complement soil inorganic information over a greater definition of scale relevant to a contact point location at a locus.