Technical note: Performing LR calculations when loci are missing between reference and trace DNA profiles

Abstract

The initial version of DNAStatistX calculated likelihood ratios (LRs) using only loci present in both the trace and reference profiles, thereby ignoring loci from the trace that are not present in the reference. Here, DNAStatistX was adapted to include all trace loci. At loci missing in the reference, an unknown contributor was invoked. Although this strategy is already incorporated in other systems, such as EuroForMix, we now explicitly study the effect on the LRs. As expected, stronger weights of evidence are achieved when all loci in the trace are included, especially when missing loci occur for a conditioned contributor.

Keywords

• Forensic science
• Probabilistic Genotyping
• Likelihood ratio
• DNAStatistX
• Missing loci