Laurance Donnelly

Soils in Forensic Science: Underground Meets Underworld

Security and environmental health issues are high on international political and social agendas, with public policy leading to legislation on environmental liability, and support for improved technologies and capabilities for use by relevant authorities. The role of soils and geological material, and their associated ecological properties, as significant sources of intelligence and physical evidence is increasingly recognised by those involved in criminal investigations. The transference of soil, or objects held within the soil matrix, has enabled associations between combinations of victim or artefact, perpetrator, and locations; demonstrable to a standard of proof and transparency required to substantiate evidence in courts of law. Formalisation of approaches to areas of search, site identification, measurement and excavation has provided a framework for structuring strategic and tactical planning of investigations. Greater attention is now being paid to new means of data capture and its interpretation, including the production of robust databases of the properties and spatial distribution of soils and underlying geological influences. Public investment is being made in research, development and operational use by investigating authorities of a toolbox of soil forensic techniques. These include isotopic analysis, non-invasive means of measurement and mapping, and the identification of properties using biological, pedological, sedimentological and geographical approaches. The advantages of integration and appropriate coupling of complementary and independent measures is now being recognised. Some tools are at a conceptual stage, such as contingency planning for mass graves, and others experimental, such as novel taggants.

Forensic geophysics and the search of building interiors, peat bogs and water.

Geophysics is one of the assets commonly deployed in the multi-proxy search for targets buried in the ground and concealed in water, most especially associated with criminal activity (e.g. human remains, graves, weapons/explosives/contraband, toxic waste). Here, we review and provide new case studies in three environments: (1) the search for objects inside human-made structures, (2) the search for buried homicide victims and human remains at unknown locations in peat bogs, and (3) the use of water-penetrating radar (WPR) in the detection of human remains in water. The latter section is expanded to the use of WPR as a reconnaissance tool in mapping areas of thickened sediment fill in water bodies, as a possible search area for sunken and then sediment-buried objects. We introduce a new term – ‘sinkability’ – to convey the concept of subaqueous areas of soft sediment where objects such as human cadavers could reside below the sediment surface.