Overlapping application of the forensic DNA analysis workflow to buried late-medieval human skeletal remains

Molecular analyses were conducted on skeletal remains discovered in a late medieval burial site beneath the former Convent of San Francesco in Mirandola, Modena, Italy. Part of the burial ground was exposed, revealing infant and adult graves dating to the construction period of the complex (14th-15th centuries AD). Thirty graves were identified which had been buried directly in the ground. They were arranged in several strictly overlapping layers and oriented along an east-west axis in accordance with Christian tradition. The historical context is poorly documented; no archival records are available regarding the causes of death or the reasons for burial at this site. Genetic analyses were conducted to complement the ongoing archaeological and anthropological studies of the site in an attempt to reveal relationships, confirm the number of individuals, explain the burial arrangements, and reconstruct their external appearance and ancestry. Ancient DNA (aDNA) was analysed using the molecular workflow routinely adopted for forensic samples. Teeth and bones were collected. DNA was isolated using a powder-free decalcification and extraction protocol. Autosomal and Y-STR markers were genotyped and Y-haplogroups inferred. The HIrisPlex system was then used to predict eye and hair colour. The results for seventeen individuals are presented herein, alongside an evaluation of the performance of this workflow when applied to severely degraded human remains. The usefulness of the powder-free decalcification protocol was also evaluated, demonstrating its applicability to both ancient and forensic samples of buried skeletal remains recovered under comparable conditions.