California’s Pure Gold Forensics Will Begin Using STRmix™ to Interpret Mixed DNA Profiles

Pure Gold Forensics, Southern California’s only accredited, private forensic DNA laboratory, will begin using STRmix™ forensic software to resolve mixed DNA profiles in criminal investigations.

Pure Gold Forensics’ decision to use STRmix™ is based on the software’s strong track record in producing usable, interpretable, and legally admissible DNA evidence in a wide range of violent crime and sexual assault cases, as well as cold cases in which it was used to re-examine evidence originally dismissed as inconclusive.

John Buckleton DSc, FRSNZ, Forensic Scientist at the New Zealand Institute of Environmental Science and Research (ESR) and one of the developers of STRmix™, notes that since it was launched in 2012, “STRmix™ has proven to be highly effective in interpreting complex DNA evidence, contributing to the successful resolution of more than 300,000 cases worldwide.” 

Pure Gold Forensics specializes in forensic DNA testing, using the latest technology in equipment and chemistry at its AL2A accredited forensic DNA testing facility in Redlands, CA.

STRmix™ works by assessing how closely multitudes of proposed profiles resemble or can explain an observed DNA mixture. Relying on methodologies routinely used in computational biology, physics, engineering, and weather prediction, the probability of the observed DNA evidence can be calculated assuming the DNA originated from either a person of interest or an unknown donor. These two probabilities are then presented as a likelihood ratio (LR), inferring the value of the findings and level of support for one proposition over the other.

STRmix™ success in accurately analyzing complex DNA mixtures has led to its use in 68 local, state, federal, and private forensic laboratories in the U.S., as well as all nine state and territory labs in Australia and New Zealand and 14 other forensic labs in countries including the U.K., Ireland, Canada, Finland, Switzerland, and Denmark.

A new version of STRmix™, Version 2.9, was recently launched. STRmix™ v2.9 contains a number of new features, including: the introduction of a batch maker mode, allowing multiple interpretations to occur simultaneously, and database search templates; memory usage improvements, which are particularly significant in dealing with higher order DNA profile mixtures; and improvements to biological modelling calculations designed to improve the modelling of stutter peaks.

The team behind STRmix™ has also launched two related products: DBLR™, an application used with STRmix™ that allows users to undertake superfast database searches, visualize the value of their DNA mixture evidence, carry out mixture to mixture matches and kinship analyses; and FaSTR™ DNA, expert forensic software that rapidly analyzes raw DNA data generated by genetic analyzers and standard profiling kits and assigns a number of contributors (NoC) estimate.

Together, STRmix™, FaSTR™ DNA, and DBLR™ complete the full workflow(external link) from analysis to interpretation and database matching.