The Probabilistic Genotyping Software STRmix: Utility and Evidence for its Validity

• NCJ Number: 254182
• Author(s): John S. Buckleton; Jo-Anne Bright; Simone Gittelson; Tamyra R Moretti; Anthony J. Onorato; Frederick R Bieber
• Date Published: 2019
• Length: 13 pages
• Grant Number(s): 2011-DN-BX-K541
• Agencies: NIJ-Sponsored
• Publication Type: Test/Measurement; Report (Study/Research); Report (Grant Sponsored); Program/Project Description
• Award: Population Genetic Issues for Forensic DNA Profiles

Annotation

The principles behind STR mix are outlined in this study and include standard mathematics and modeling of peak heights and variability in those heights.

Abstract

Forensic DNA interpretation is transitioning from manual interpretation based usually on binary decisionmaking toward computer based systems that model the probability of the profile given different explanations for it, termed probabilistic genotyping (PG ). Decisionmaking 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. 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, STR mix. A current issue is access to the code and quality processes used while coding. There are substantial data that describe the performance, strengths, and limitations of STR mix, one of the available PG software. (publisher abstract modified)