Mass grave complexity effects on the minimum number of individuals estimation

This study analyses the accuracy of the minimum number of individuals (MNI) estimation in the context of commingled human remains recovered from secondary mass graves related to the war in Bosnia in 1995. It is based on data from five secondary mass grave sites of different sizes and different numbers of unassociated body parts. The study is centered on a comparison of MNI estimation from original excavations with the actual number of individuals buried in particular graves, obtained via DNA identification of excavated remains. The aim was to investigate how the complexity of a mass grave reflects on MNI estimation accuracy. In order to quantify mass grave complexity (level of commingling), a ratio between complete bodies and isolated body parts from the same context was introduced. Results show that, in the secondary mass graves involved in the study, MNI estimation inaccuracy varies in the range from 54% to 513% depending on the size of the grave itself and the amount of "loose elements" distributed in it. Correlation between MNI inaccuracy and body to body parts ratio shows a strong relationship indicating that MNI (in)accuracy is largely dependent on the number of loose elements related to complete bodies from the same context.