Searching CODIS with binary conversions of STRmix interpretations

The predominant approach to interpreting autosomal STR DNA typing results is through the use of probabilistic genotyping software. The primary output from such software is a list of genotypes and associated genotype weights representing the likelihood of observing the typing results if an individual or set of individuals with that genotype(s) was the donor of the evidence DNA. While such lists are used by probabilistic software to calculate likelihood ratios based upon a pair of propositions regarding specific donors of the DNA, they are not directly amendable to entry into law enforcement databases that use the Combined DNA Index System (CODIS) software. An approach to creating CODIS-compatible profiles from the output of the probabilistic genotyping program STRmix is discussed and assessed for sensitivity and specificity. Combining this information with an assessment of the weight-of-evidence potential contained in the STRmix interpretation, pragmatic guidance was developed regarding the creation and searching of CODIS profiles in a way that balances the detection of investigative leads with the potential burdensome effects on workload.