Keeping the pieces together: comparison of mass grave excavation methodology.
Mass graves are a complex and confusing mix of bodies, body parts, soils, artifacts, and other feature evidence. Forensic investigations of these complex crime scenes should attempt to maximize the collection of evidence, which includes the mortal remains, in their best possible condition as they were deposited within the graves. Two standard methods of mass grave excavation were examined with the aim of identifying the better approach. Two experienced teams using different methodologies excavated two separate but very comparable mass graves located in the same area. Single disarticulated skeletal elements not associated with a body at the time of removal from the grave were categorized and their counts analyzed to evaluate the efficiency of the differing excavation methodologies. The methodologies used were the 'pedestal' method, which focuses on the body mass, and the 'stratigraphic' method, in which the grave feature and contents are conjointly excavated. The first grave (Grave A), excavated using the 'pedestal' method, was observed to have a disproportionately larger amount of unassociated bones than did the second (Grave B), which used the 'stratigraphic' method. Chi-square (chi2) goodness-of-fit and contingency tests were performed on the total numbers of recorded elements and different categorical groups of bones, based on size and shape, in each grave. Results demonstrate that significantly greater numbers of unassociated elements resulted from the excavation of Grave A using the pedestal method, both in total number of disarticulated bones as well as within 'large' and 'medium' categories. Conversely 'small' skeletal elements were recovered at a higher rate in Grave B. The lower 'large' and 'medium' bone production rates from Grave B indicate that the stratigraphic method better maintained the provenience and articulation of remains than did Grave A, while the higher 'small' bone recovery rate may point to better recovery techniques of Grave B's excavation team.