18-May-2023

Response to Thompson article in the Journal of Forensic Sciences

Last year Cybergenetics prepared a TrueAllele match report for a California defendant. Using all the DNA data, TrueAllele technology found a strong exclusionary likelihood ratio (LR) of 1 over a million. Using just 10% of our input data, a New Zealand genotyping program (STRmix) found a weaker LR around 1 in ten. As expected, using more input data gave more output information.

To block the exculpatory software results, the prosecutor retained Bill Thompson. Thompson, an academic and a lawyer, prepared a partisan report opposing the DNA. His faulty premise was that both programs should have given the same LR values. From that flaw, his report made many inaccurate statements about TrueAllele, how it works, and what it finds. His report wasn’t used, and (thanks to TrueAllele) the DNA-related charges were dropped.

Cybergenetics has responded to Thompson. Our manuscript accurately explains the science behind the software methods. Examining the case data input, we show why the two programs should output different LR values. We address 20 misleading concepts and respond to 120 of his statements. Anyone puzzled by Thompson’s polemic will find helpful answers in our corrective response.

Links

• Reporting exclusionary results on complex DNA evidence, a case report response - SSRN