STRmix Highly Effective in Producing Interpretable, Admissible DNA Results

STRmix™ Version 2.9, the newest version of the groundbreaking forensic software used to resolve mixed DNA profiles previously considered too complex to interpret, will be launched today.


Since its introduction in 2012, STRmix™ has proven to be a highly effective tool in producing usable, interpretable, and admissible DNA results in a wide range of criminal cases, including violent crime and sexual assault cases. It has also been instrumental in helping to solve cold cases in which evidence originally was dismissed as inconclusive.


STRmix™ Version 2.9 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.


Some of the new features contained in STRmix™ v2.9 were made in response to recommendations made by the forensic laboratories currently using the software.  “These changes will enable those labs to better address the on-the-job needs they regularly encounter,” says Dr. Jo-Anne Bright, Senior Science Leader at the New Zealand Institute of Environmental Science and Research (ESR) and one of the developers of STRmix™.


Noting that the latest version of STRmix™ underwent more than a year of extensive development and testing, Dr. Bright explains that demand for the software “continues to be extremely high due to the critical role it plays in helping to solve crimes and excluding individuals who have been wrongly associated as the source of crime scene evidence.”


To date, STRmix™ has been used to interpret DNA evidence in more than 300,000 cases worldwide. That number includes numerous U.S. court cases, including at least 83 successful admissibility hearings.


STRmix™ works by assessing how closely multitudes of proposed profiles resemble or can explain an observed DNA mixture. Using well-established statistical methods 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.


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.

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