Second GHEP-ISFG exercise for DVI: "DNA-led" victims' identification in a simulated air crash.

The Spanish and Portuguese-Speaking Working Group of the International Society for Forensic Genetics (GHEP-ISFG) has organized a second collaborative exercise on a simulated case of Disaster Victim Identification (DVI), with the participation of eighteen laboratories. The exercise focused on the analysis of a simulated plane crash case of medium-size resulting in 66 victims with varying degrees of fragmentation of the bodies (with commingled remains). As an additional difficulty, this second exercise included 21 related victims belonging to 6 families among the 66 missings to be identified. A total number of 228 post-mortem samples were represented with aSTR and mtDNA profiles, with a proportion of partial aSTR profiles simulating charred remains. To perform the exercise, participants were provided with aSTR and mtDNA data of 51 reference pedigrees -some of which deficient-including 128 donors for identification purposes. The exercise consisted firstly in the comparison of the post-mortem genetic profiles in order to re-associate fragmented remains to the same individual and secondly in the identification of the re-associated remains by comparing aSTR and mtDNA profiles with reference pedigrees using pre-established thresholds to report a positive identification. Regarding the results of the post-mortem samples re-associations, only a small number of discrepancies among participants were detected, all of which were from just a few labs. However, in the identification process by kinship analysis with family references, there were more discrepancies in comparison to the correct results. The identification results of single victims yielded fewer problems than the identification of multiple related victims within the same family groups. Several reasons for the discrepant results were detected: a) the identity/non-identity hypotheses were sometimes wrongly expressed in the likelihood ratio calculations, b) some laboratories failed to use all family references to report the DNA match, c) In families with several related victims, some laboratories firstly identified some victims and then unnecessarily used their genetic information to identify the remaining victims within the family, d) some laboratories did not correctly use "prior odds" values for the Bayesian treatment of the episode for both post-mortem/post-mortem re-associations as well as the ante-mortem/post-mortem comparisons to evaluate the probability of identity. For some of the above reasons, certain laboratories failed to identify some victims. This simulated "DNA-led" identification exercise may help forensic genetic laboratories to gain experience and expertize for DVI or MPI in using genetic data and comparing their own results with the ones in this collaborative exercise.

Large scale DNA identification: The ICMP experience.

The International Commission on Missing Persons (ICMP) is a treaty-based international organization with a global mandate to address the issue of missing persons. It works with governments, civil society organizations, and others, and utilizes data systems and technical assistance in forensic science. ICMP's initial work focused on the ∼40,000 people missing in the Western Balkans from the conflicts of the 1990s. A "DNA-led" approach to large-scale DNA identification of the missing was developed, based on high-throughput autosomal STR testing of skeletal remains from mass graves and other sites, and the establishment of a regional database of DNA profiles from family members of the missing. Database pairwise and pedigree kinship searching is conducted using in-house DNA matching software, the Identification Data Management System (iDMS), providing high-certainty DNA matches that are integrated in a multi-disciplinary identification process. Anthropological guidelines for sampling skeletal remains for DNA testing are based on tens of thousands of tests from a wide range of skeletal elements, allowing for prioritization based on DNA preservation. Large-scale collection of family reference samples has been conducted, resulting in a database of more than 100,000 family reference DNA profiles across all projects and delivering family DNA match reports for more than 20,000 individuals. From the 1995 Srebrenica event, ICMP provided DNA matches for 6887 of the ∼8000 missing from that event. In assistance to justice, ICMP has provided extensive evidence and expert testimony in multiple war crimes trials, including those conducted at the ICTY. This article provides an overview of ICMP's technical involvement over the last 17 years in areas of DNA testing and database matching, and training and capacity building projects with partners. It also touches on the development of massively parallel sequencing (MPS) strategies specifically tailored to missing persons applications.