Evaluation of DNA mixtures accounting for sampling variability

Abstract

In the conventional evaluation of DNA mixtures, the allele frequencies are often taken as constants. But they are in fact estimated from a sample taken from a population and thus the variability of the estimates has to be taken into account. Within a Bayesian framework, the evaluation of DNA mixtures accounting for sampling variability in the population database of allele frequencies are discussed in this paper. The concise and general formulae are provided for calculating the likelihood ratio when the people involved are biologically related. The implementation of the formula is demonstrated on the analysis of a real example. The resulting formulae are shown to be more conservative, which is generally more favorable to the defendant.