Forensic Genetics at the Service of Disaster Victim Identification: The Preliminary Results of the Experimental Mass Grave Project

The need to identify victims of mass disasters (Disaster Victim Identification - DVI) represents a challenge for forensic investigations. Developing and validating strategies for DVI is critical for humanitarian, ethical and legal reasons. Every disaster has its scenario, and every scenario defines its own methods for identifying corpses. The use of genetic profiling as the main means of identification has been suggested more than twenty years ago and reinforced following the terrorist attack on the World Trade Center, as it is not only able to provide a precise identification, but also to associate the remains. To date, DNA extraction from human remains in an advanced state of decomposition or skeletonization is made using mostly sampling "hard" tissues such as bones and teeth. The study originates from the "Experimental Mass Grave Project" (MGP) conducted at the Forensic Anthropology Center of Texas State University (FACTS), research aimed at studying at a macroscope, microscopic and biomolecular level the entire process of decomposition of human bodies within mass graves and individual tombs. In particular, the forensic geneticists involved in the study carried out sampling to assess the completeness of the genetic information obtained from skin, oral and rectal swabs made upon arrival of the donors to the FACT and after their freezing lasted from 11 to 455 days. Subsequently, the possibility of typing genetic profiles useful for a comparison starting from soft tissues/ biological fluids sampled after 18 months of burial was evaluated, also checking if there was a correlation between the goodness of the genetic profiles obtained and the degree decomposing, the characteristics of the burial and the location of the donor in the mass grave. The results of the study show a progressive loss of information with the freezing of the bodies and their burial. In addition, the results obtained from exhumation samples do not seem to be affected by the degree of decomposition of the body and its position inside the mass grave. In the mass grave, higher levels of preservation of bodies than in individual graves, cross-contamination of biological material and less DNA degradation were observed. In conclusion, the study made it possible to understand how freezing and burial can influence the personal identification of corpses in particular contexts such as mass disasters and at the same time stresses the importance, in these circumstances, of sampling how many as many tissues as possible in order to successfully identify an unknown corpse.