Analysis of complex DNA mixtures using massively parallel sequencing of SNPs with low minor allele frequencies

•Identified as many as 10 people in realistic touch samples recovered from a variety of materials.•At least 1 true positive was detected in 96 of 100 multi-contributor touch samples.•Four to 10 people were detected in 34 of the touch samples when using -Log P(RMNE)=6. DNA mixtures from 3 or more contributors have proven difficult to analyze using the current state-of-the-art method of short-tandem repeat (STR) amplification followed by capillary electrophoresis (CE). Here we analyze samples from both laboratory-defined mixtures and complex multi-contributor touch samples using a single nucleotide polymorphism (SNP) panel comprised of 2311 low-minor-allele-frequency loci, combined with massively parallel sequencing (MPS). This approach demonstrates that as many as 10 people can be identified in touch samples using a threshold of -Log P(RMNE) of 6, and a detection rate of 18–94 % across 10 different materials using a threshold of -Log P(RMNE) of 2. Thirty-two false positives were observed in 100 touch samples.