Analysis of soil samples for forensic investigations

Soil science is an emerging discipline in forensics, where Locard’s Principle that every contact leaves a trace is a key concept. Soil analysis is used either to link a soil sample to a crime scene or piece of evidence to the exclusion of all other samples (individualisation) or to establish whether two samples have a common source (comparison). The analysis methods used are often limited by time constraints, expertise, laboratory equipment and the mass of sample available. However, several approaches use equipment and consumables that are often readily available in a standard laboratory for conducting soil analysis. Thus, soil scientists can apply their knowledge and laboratory expertise for use in forensics. This paper describes and critically discusses methods of physical, chemical and biological soil analysis that are commonly applied when collecting evidence in criminal cases. Finally, their real-world application is highlighted using three example criminal case studies.