A fully continuous system of DNA profile evidence evaluation that can utilise STR profile data produced under different conditions within a single analysis. (November 2017) - Taylor, Duncan
Highlights: We explain several casework situations that can arise which require evaluation of DNA profile replicates that span a technology change. When a likelihood ratio is required for these types of evaluations, the classic approach has been to pick one of the replicates. We present the maths for the interpretation system STRmix™ to allow the combination of replicates produced under different conditions. We demonstrate the performance of the proposed model on situations which may be encountered in the laboratory. Abstract: The introduction of probabilistic DNA interpretation systems has made it possible to evaluate many profiles that previously (under a manual interpretation system) were not. These probabilistic systems have been around for a number of years and it is becoming more common that their use within a laboratory has spanned at least one technology change. This may be a change in laboratory hardware, the DNA profiling kit used, or the manner in which the profile is generated. Up until this point, when replicates DNA profiles are generated, that span a technological change, the ability to utilise all the information in all replicates has been limited or non-existent. In this work we explain and derive the models required to evaluate (what we term) multi-kit analysis problems. We demonstrate the use of the multi-kit feature on a number of scenarios where such an analysis would be desired within a laboratory. Allowing the combination of profiling data that spans a technological change will further increase the amount of DNA profile information produced in a laboratory that can be evaluated.