Combined application of multiple autosomal and Y-chromosomal STR loci in solving a homicide case in 2009

In 2009, a violent murder occurred. Two victims, a 47-year-old mother and her 21-year-old daughter, were murdered at home. After importing the 20 autosomal STR loci and 27 Y-STR loci into a database, no hit had been found. In 2019, a person with a prior criminal record was matched in the national forensic Y-STR database. When increasing the number of detected Y-STR loci to 60, all loci of the bloodstain donor at the crime and the suspect were still found to be identical. With the combined calculation of multiple autosomal STR and kinship index, we were able to identify the perpetrator as a previously unknown illegitimate child of a large family and solved the case.