Twelve-year experience in identification of skeletal remains from mass graves.

Aim: To present twelve-year (1993-2005) experience in identification of human remains found in mass graves in Croatia and Bosnia and Herzegovina (BH), as well as remains that presumably belonged to Croatian citizens given by Serbia and Montenegro. The unique experience of identification of more than a thousand of skeletal samples is valuable for better organization of post-mortem identifications.

Methods: Standard forensic methods and methods based on DNA analysis were used for identification of human remains from mass graves. DNA was isolated using standard phenol/chloroform/isoamyl alcohol extraction. In some cases, decalcification and repurification were used prior to the extraction to overcome inhibition of amplification process. Different DNA systems were used for DNA quantitation and amplification (AluQuant, short tandem repeats (STR) commercial systems, Y chromosome STRs, and mitochondrial DNA [mtDNA]). Typing of PCR products was performed on AmpliType PM and AmpliType DQA1 DNA probe strips, ABI PRISM(R) 310 Genetic Analyzer and immobilized sequence-specific oligonucleotide (SSO) probes.

Results: Up-to-date analysis of 1,155 skeletal samples resulted in 703 positively identified bodies: 577 using standard forensic methods, 109 by DNA typing, and 17 by combination of these two methods. The majority of identifications from 1993 to 1999 was, as usual, achieved by standard forensic methods. Later on, these methods were not sufficient and DNA analysis was requested. It was performed in 42% of all cases in 12 years. The crucial step in DNA analysis is extraction of genomic DNA. Standard phenol/chloroform/isoamyl alcohol extraction, complemented with other methods and modifications, proved as the most successful method for this step. In certain cases, the quality and/or quantity of nDNA was not satisfying and the analysis of the mtDNA was performed.

Conclusion: Our experience demonstrated that the advent of forensic DNA analysis methods greatly increased our ability to positively identify previously unknown skeletal remains by a comparative genetic analysis with presumptive relatives.