The application of soil analysis in forensic taphonomy: using pigs as analogues for human corpses

Many studies have shown how Environmental Sciences can contribute to the forensic and medico-legal investigations on murder and body concealment dynamics. Nonetheless, most of the research is generally limited to botanical, entomological and anthropological fields leaving out the observation of the active interaction between a decomposing body and the surrounding environment, such as soil. Indeed, a clandestine grave can destroy the valuable forensic evidence as well as prevent the identification of the offender or the victim itself and even the determination of the post-mortem interval (PMI), post-burial interval (PBI) and, overall, the dynamics of the crime act. Therefore, the present experiment, built on the basis of a previous pioneer project carried out in the same area between 2009 and 2011, will be based on the re-enactment of real cases of body disposal, consisting in a combination of multiple methods of concealment, all of them including the inhumation of the remains in a woodland setting. It will consist of the excavation of 32 burials, all dug on the same day, at a depth between 40 and 60 cm involving just as many piglet cadavers (Sus scrofa) weighing between 3 and 5 kg. They will be divided into four different groups, each of which will undergo peculiar treatments: eight will be buried naked; eight clothed; eight will be buried in quicklime and the last eight will be previously hurt. The experiment will be conducted for a total of 730 days and the exhumations of the specimens will be performed in eight increasing time intervals, to achieve different PBIs for each group of subjects (15, 30, 60, 120, 240, 365, 545 and 730 days). At the time of each exhumation biological material, commodities and soil will be sampled and investigated from a geochemical, microscopic (polarizing microscope) and ultramicroscopic (SEM-EDS) point of view, aiming to underline any evidence of mutual exchange of material between the different substrates, as well as any symptom of disturbance, both biochemical and mechanical. As focusing on a multidisciplinary approach, not only this study will allow to reach a standardization for the right reading of trace evidence in real cases of clandestine burials inquiry, but it also will contribute to draw up some guidelines for the exploitation of the parameters registered by the geopedological analytical techniques, which have been neglected for years in the forensic and medico-legal context.