The probabilistic genotyping software STRmix: Utility and evidence for its validity (Accepted Manuscript)

Forensic DNA interpretation is transitioning from manual interpretation based usually on binary decision making towards computer based systems that model the probability of the profile given different explanations for it, termed probabilistic genotyping (PG). Decision making by laboratories to implement probability-based interpretation should be based on scientific principles for validity and information that supports its utility, such as criteria to support admissibility. The principles behind STRmix^TM are outlined in this paper and include standard mathematics and modeling of peak heights and variability in those heights. All PG methods generate a likelihood ratio (LR) and require the formulation of propositions. Principles underpinning formulations of propositions include the identification of reasonably assumed contributors. Substantial data have been produced that support precision, error rate, and reliability of PG, and in particular STRmix™. A current issue is access to the code and quality processes used whilst coding. There are substantial data that describe the performance, strengths and limitations of STRmix™, one of the available PG software.