Clandestine Graves of Homicide Victims

Accurate determination of both the post mortem and post-burial interval (PMI/PBI) of a clandestine grave of a homicide victim is critical for forensic investigators to link or eliminate suspect(s). Currently, detection rates worldwide are low using a variety of search methods, ranging from simple ground probing and use of scent-trained search dogs, to more advanced remote imagery analysis and near-surface geophysics techniques. In this collaborative study, three simulated clandestine graves of murder victims were emplaced in test site locations with contrasting soil types (made ground, sandy and peat), bedrock and depositional environments (semi-urban, rural and moorland) respectively. Long-term monthly in situ monitoring of grave soilwater, extracted using lysimeters, all revealed rapid increases in conductivity up to two years after burial, with the longest study evidencing declining conductivity values down to background levels after 4.25 years of burial until the end of the survey period. All results were corrected for site temperatures (accumulated degree days) and average site rainfall to allow generic models of fluid conductivity as a function of time to be generated. Research implications suggest this simple method gives a reliable PMI/PBI date of a discovered clandestine grave, with soilwater conductivity also a potential grave detection method. .