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Forensic Software Enhanced for Resolving Degraded or Mixed DNA Samples

STRmix™ v2.11 has enhanced memory use as well as other general improvments to the models

DNA strand made of light

The new features in STRmix™ v2.11 were made primarily in response to recommendations made by the forensic laboratories currently using the software, allowing them to better address on-the-job needs they regularly encounter.

by STRmix
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WASHINGTON, DC — The STRmix team has launched the latest version of its groundbreaking software for resolving low-level, degraded, or mixed DNA samples from multiple contributors. 

STRmix™ version 2.11 features enhancements to memory use, general improvements to the models and model maker, and the inclusion of an upper bound to the HPD likelihood ratio (LR). Its most significant change, however, is the addition of Amelogenin into the deconvolution and LR. 

“These changes, coupled with other recent improvements such as v2.10’s introduction of a Visualize Weights module to help analysts investigate DNA interpretation results, make it easier for forensic labs to produce highly usable, interpretable, and legally admissible DNA results in a wide range of criminal cases, including violent crime, sexual assault, and cold cases,” says STRmix team Senior Science Leader and co-developer of STRmix™, Dr. Jo-Anne Bright. 

The new features in STRmix™ v2.11 were made primarily in response to recommendations made by the forensic laboratories currently using the software, allowing them to better address on-the-job needs they regularly encounter.

Unlike previous methods of DNA analysis, which depended entirely on the application of fixed stochastic thresholds and other biological parameters to manually analyze DNA samples, STRmix™ assesses how closely a multitude of potential DNA profiles resemble or can explain an observed DNA mixture.

Relying on proven methodologies routinely used in computational biology, physics, engineering, and weather prediction, STRmix™ calculates the probability of observed DNA evidence by assuming the DNA originated from either a person of interest or an unknown donor. These two probabilities are then presented as a LR, which infers the value of the findings and the level of support for one proposition over the other.

The success of that methodology in resolving DNA profiles previously considered too complex to interpret has led to the adoption and use of STRmix™ by 106 forensic organizations around the world, including 80 local, state, and federal agencies in the US. Since its introduction in 2012, STRmix™ has been used to interpret DNA evidence in more than 380,000 cases worldwide. 

In addition to STRmix™ v2.11, the STRmix team has developed and previously launched two related software applications: 

  • DBLR™, an application that when used with STRmix™ allows forensic laboratories to undertake extensive kinship analysis, carry out rapid database searches, visualize the value of their DNA mixture evidence, and carry out mixture-to-mixture matches; and
  • FaSTR™ DNA, expert forensic software that seamlessly integrates with STRmix™ (when in use) to rapidly analyze raw DNA data generated by genetic analyzers and standard profiling kits and assigns a number of contributors (NoC) estimate. 

In combination with STRmix™, these applications complete the full workflow from analysis to interpretation and database matching. 

STRmix Limited recently announced that all three of its software packages will continue to be distributed in North, South, and Central America by Ohio-based NicheVision Forensics, LLC. Founded in 2007, NicheVision has had exclusive distribution rights to STRmix™ in the Americas since 2014.