Spatial thinking in search methodology: A case study of the 'no body murder enquiry', West of Ireland

Abstract

Geographical information systems (GIS), recognised as instrumental in the documentation, mapping and analysis of spatial crime data, can provide a framework for the integration and analysis of spatial data whether remotely generated on a regional scale, ground surveyed or sampled on a local scale at a crime scene. In this paper a missing person homicide case study is discussed to illustrate the role of spatial thinking in search methodologies and the application of GIS and spatial analysis techniques. Differential global positioning systems were used to collect data from an area of mixed moorland, bog and agricultural ground in the west of Ireland where police intelligence suggested human remains may have been hidden by a murderer. These data allowed the creation of a digital terrain model (DTM) at a resolution not achieved by conventional terrain mapping. The resultant topographic maps and 3D visualisations allowed a sector, or topographic domain, approach to be used at a scale finer than usual in geomorphology. This in turn allowed small water catchments to be defined. These data informed the sampling of shallow groundwater for carbon content and isotope analysis. Two anomalies were indicated, in places consistent with known criminal behaviour. The locations were surveyed by a ground penetrating radar system, and by a cadaver dog. Ground penetrating radar (GPR) failed to indicate any subsurface disturbance or grave, yet the cadaver dog indicated a point of interest close to the location of one anomaly identified from groundwater sampling. Further searching near this location failed to discover human remains, yet the isotope, topography and dog indications showed that some anomaly existed. This finding may be a false-positive, the result of previous excavation activity or that the remains had 'returned to earth', in the light of the missing person never having been found. Regardless, the spatial search methodology described is an innovative combination of new technology, traditional landscape interpretation and hydrological chemical analysis. Adaptation, testing and use of this protocol for similar searches are recommended. The approach also has broader application to environmental, humanitarian and military investigations.