A Complementary Approach to the Forensic Analysis of Soil in Case Investigations.

Soil is a complex and heterogeneous material.  However, that complexity can make it a useful form of trace evidence. This talk will illustrate how soil information can be used both in the intelligence and evidential phases of a criminal investigation. It will outline a complementary approach to soil analysis using both inorganic and organic signatures. Soil is unlikely to be the only form of evidence used, but it can be very powerful when brought together with other pieces of information in the investigation jigsaw. This will be illustrated with reference to case work, and in particular, two recent high profile cases from the U.K.

In a recent  large scale murder hunt led by Northern Constabulary, soil information was used in the search phase of the investigation, to help eliminate areas of land using Geographical Information Systems, and to help with the construction of probable pattern of vehicle movements. It was also used as evidence, through a two way association. Sand from the deposition site was found on the spade, and flakes of metal from the spade were found at the deposition site, making a strong contact trace association. Two men were found guilty of murder and culpable homicide.

In 2007, an aggravated burglary took place at a home in Derbyshire. Police traced the suspect vehicle and footwear was recovered. Detectives were able to piece together a sequence of events which linked the offenders to the scene of crime, through use of a combination of evidence types.  The CCTV showed the offenders wearing certain distinctive items of footwear as they were disposing of their stolen money. DNA evidence linked the offenders to those specific items of footwear, while the soil on the soles of the footwear linked them to the scene of crime, and vegetation found on the footwear complemented the soil evidence to piece together an entry and exit route. Three out of four were arrested and received substantial custodial sentences. The fourth absconded abroad.

Acknowledgements: RERAD and EPSRC for funding the research.