DNA

Until recently, identification of the remains of missing persons was largely based on methods such as comparing ante-mortem and post-mortem information, including age and stature, combined with evidence of clothing or personal items found with the victims. In some cases, these methods may be complemented by the use of fingerprint technology and the analysis of dental records.

Today, identification of the remains of large numbers of missing persons is best performed via DNA analysis, preferably in conjunction with other available records as defined above. This method is objective, scientifically accurate and cost effective. Typically, DNA-based identifications of large numbers of missing persons involve DNA screening of family members and a comparison of their DNA with that obtained from the recovered remains of the missing. The process relies on the participation of relatives of the missing, as well as that of the courts and other local authorities.

The ICMP DNA laboratory system consists of two facilities, which operate under a well established quality management system and are accredited by an internationally recognized accreditation body. The DNA laboratories daily perform 105 DNA extractions, usually from bone or tooth samples taken from the mortal remains of missing persons. DNA extraction of bone uses a specially adapted “silica-binding” method with a high success rate for nuclear DNA short tandem repeats (STRs) that are commonly used for forensic DNA profiling. The DNA extracts are then quantified to determine the amount of usable DNA recovered. Often only small numbers of surviving DNA molecules are recovered (and in some cases the samples contain no usable DNA). Because the samples often contain only trace amounts of DNA, processing requires the utmost care and expertise to exclude contaminating DNA from sources other than the samples themselves. The STR DNA profiles are obtained from the DNA extracts via Polymerase Chain Reaction amplification using the Promega PowerPlex 16 (PP16) kit, or an ICMP-developed “mini-amplicon” STR kit for highly degraded samples. The Applied BioSystems IdentiFiler kit can also be used. The DNA of family members is usually obtained from blood samples, and is processed in a high-throughput mode that has generated nearly 90,000 family reference profiles to date.

The DNA profiles of missing persons and those of family members are compared as part of an identification coordination process for the purpose of making kinship-based identifications. ICMP uses a custom matching program that searches for direct matching, half allele share that is required for a parent-child relationship, as well as sibling indices, and is generally indicative of genetic relatedness. Final kinship statistics are generated using the software program DNAView.

DNA Match Reports are issued for those matches with a statistical significance of 99.95% or greater, with prior probability very generally calculated as the number of missing from a particular region.