Commentary on: Thompson WC. Uncertainty in probabilistic genotyping of low template DNA: A case study comparing STRmix™ and TrueAllele®. J Forensic Sci. 2023;68(3):1049–63

Author's response

“…Based on this statement a casual reader might assume that the eight validation studies Perlin et al [3] cited actually tested TA's accuracy for low-level samples like the one discussed in my article and found that TA was accurate. That would be a mistake.…”

“…Perlin et al [3] do not respond to this evidence; they offer no arguments for ignoring it. Instead, they simply say that I cited only three of "eight peer-reviewed studies validating TA interpretations for mixtures containing 2 to 10 unknown contributors" [3].…”

“…It also questioned the way these findings were reported. Individuals associated with both STRMix [2] and TA [3] have now responded to my article. They presented new data that helped explain why the LRs produced by the programs were so different.…”

“…I agree with this assessment and I believe that a key source of uncertainty about the value of PG results in the case I discussed is that relatively little research of this type has been done. By contrast, the group led by Mark Perlin, one of the creators of TA, sees no need for analytic thresholds, saying that "TA is a fully Bayesian system capable of looking at all the peak data…" [3]. While I certainly accept that TA is capable of producing LRs based on lowlevel data, I question whether such results are always reliable and trustworthy.…”

“…For example, my article cited research showing that TA produced falsely exculpatory LRs for some known contributors, including the majority of individuals who contributed less than 10 pg to a mixture in one study [5]. Perlin et al [3] do not respond to this evidence; they offer no arguments for ignoring it. Instead, they simply say that I cited only three of "eight peer-reviewed studies validating TA interpretations for mixtures containing 2 to 10 unknown contributors" [3].…”