Getting the conclusive lead with investigative genetic genealogy - A successful case study of a 16 year old double murder in Sweden.

On the morning of October 19, 2004, an eight-year-old boy and a 56-year-old woman were stabbed to death on an open street in the city of Linköping, Sweden. The perpetrator left his DNA at the crime scene, and after 15 years of various investigation efforts, including more than 9000 interrogations and mass DNA screening of more than 6000 men, there were still no clues about the identity of the unknown murderer. The successful application of investigative genetic genealogy (IGG) in the US raised the interest for this tool within the Swedish Police Authority. After legal consultations it was decided that IGG could be applied in this double murder case as a pilot case study. From extensive DNA analysis, including whole-genome sequencing and genotype imputation, DNA data sets were established and searched within both GEDmatch and FamilyTree DNA genealogy databases. A number of fairly distant relatives were found from which family trees were created. The genealogy work resulted in two candidates, two brothers, one of whom matched the crime scene samples by routine STR profiling. The suspect confessed the murders at the initial police hearing and was later convicted of the murders. In this paper we describe the successful application of an emerging technology. We disclose details of the DNA analyses which, due to the poor quality and low quantity of the DNA, required reiterative sequencing and genotype imputation efforts. The successful application of IGG in this double murder case exemplifies its applicability not only in the US but also in Europe. The pressure is now high on the involved authorities to establish IGG as a tool for cold case criminal investigations and for missing person identifications. There is, however, a continuous need to accommodate legal, social and ethical aspects as well.

Whole-genome sequencing of human remains to enable genealogy DNA database searches - A case report.

Recently a number of high profile crime cases (e.g. the "Golden State Killer") have successfully been solved or given new leads with the use of genome wide DNA data in combination with pairwise matching from individuals present in genealogy DNA databases. Such databases will primarily involve distant relatives which in turn require a large amount of genetic information, in the range of several hundred thousand to millions of SNPs, to be genotyped. While it nowadays is fairly straightforward to obtain such as data from high quality and high quantity DNA, it is still a challenge for degraded DNA of low quantity such in the case of forensic samples. Here we present a successful effort in obtaining genome-wide genotype data from human remains. The goal was to get investigative leads in order to identify the remains of an unknown male ("the Ekeby man") that was found murdered in the south of Sweden in 2003. Whole-genome sequencing was performed on DNA originating from a bone sample. Three replicates of libraries were prepared using ThruPLEX DNA-seq Kit (Takara) which were sequenced on a HiSeq X instrument (Illumina). A mean coverage of 30X was obtained when the sequencing reads were mapped to a human reference genome. Following further bioinformatic processing, allele calling, quality checks and filtering to match the genealogy DNA database SNPs, genotypes for approximately one million SNPs were established. The resulting SNP genotypes were then used to search for relatives in the genealogy DNA database GEDmatch (www.gedmatch.com). A candidate list of relatives was obtained which was further processed using traditional genealogy methods in order to get leads about the identity of the unknown. In summary, this report shows how whole-genome sequencing successfully can be applied on forensic samples to create the SNP genotypes required for searches in genealogy DNA databases for the purpose of generating leads to identify missing or unknown persons, including perpetrators and victims.