Following approval for use by the Los Angeles County Sheriff’s Department and Washington State Patrol, STRmix™ – the sophisticated forensic software used to resolve mixed DNA profiles previously thought to be too complex to interpret – has been approved for use by Signature Science and the San Francisco Police Department (SFPD).
A subsidiary of the Southwest Research Institute based in Austin, TX, Signature Science is a scientific and technical consulting firm, providing multi-disciplinary applied research, technology design and development, and scientific, technical, and operational services to government and industry.
SFPD is the city police department for both the City and County of San Francisco, CA, and the 11th largest police department in the United States, serving an estimated population of 1.2 million, including the daytime-commuter population and thousands of other tourists and visitors.
STRmix™: What is it?
(STRmix™ is an “expert software system” designed by researchers at ESR and Forensic Science South Australia (FSSA), used by DNA reporting analysts for the interpretation of forensic DNA profiles, with particular application to complex DNA mixtures with no restriction on the number of contributors. Courtesy of KiwiNetTV and YouTube. Posted on Jul 13, 2017.)
STRmix™ is a forensic software used by trained, experienced DNA experts to STRmix™, allowing a DNA profile to be matched directly against a database.
With STRmix™ Law Enforcement is Able To:
- Interpret DNA results faster
- Combine DNA profiles from different kits in the same interpretation
- Compare profiles against a person of interest and calculate a likelihood ratio
- Resolve previously unresolvable, complex DNA mixtures with no restriction on the number of contributors
- Use more of the information in a DNA profile
- Search complex, mixed DNA profiles against a database
The latest version of STRmix™, introduced in mid-2017, contains new features designed to improve functionality, speed, memory, and ease of use, including multi-kit functionality which enables interpretation of DNA profiles from different test kits and a likelihood ratio (LR) batcher tool, which allows users to calculate multiple LRs from multiple reference inputs to a previously run deconvolution.
(Learn More about ESR STRmix™: Resolve More DNA Mixtures. Courtesy of KiwiNetTV and YouTube. Posted on Jun 17, 2015.)
Thirty-six federal, state, and local agencies throughout the U.S. now routinely use STRmix™ to resolve DNA profiles, including the Federal Bureau of Investigation (FBI) and the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF).
STRmix™ is also in use in 14 labs in Australia, England, Scotland, Ireland, Canada, and New Zealand, and in various stages of installation, validation, and training in more than 50 other U.S. labs.
“Since its introduction in 2011, STRmix™ has gone from being regarded as an experimental technology to the broadly accepted norm in cases in which forensic DNA software is required to resolve mixed DNA profiles,” says John Buckleton DSc, FRSNZ, Forensic Scientist at the New Zealand Institute of Environmental Science and Research (ESR).
Dr. Buckleton developed STRmix™ in collaboration with ESR’s Jo-Anne Bright and Duncan Taylor from Forensic Science South Australia (FSSA).
STRmix™ works by using standard, well-established statistical methods to build up a picture of DNA genotypes that, when added together, best explain an observed mixed DNA profile.
STRmix™ then enables users to compare the results against a person or persons of interest and calculate a statistic, or “likelihood ratio,” of the strength of the match.
To date, STRmix™ has been used successfully in numerous U.S. court cases – including 22 successful admissibility hearings – and about 100,000 cases internationally.
“Most recently, STRmix™ was used to provide DNA evidence which led to the convictions of a Brooklyn, NY man accused of murdering his estranged wife and two Florida men accused in the fatal drive-by shooting of a toddler,” explains Martin Riegel, Chief Executive Officer of STRmix™ Ltd., the newly formed subsidiary of ESR.
(Learn More. Kquame Richardson and Henry Hayes IV were convicted of first-degree murder and other charges in the January 2016 shooting death of 22-month-old Aiden McClendon. Courtesy of WJXT – News4Jax and YouTube. Posted on Jul 3, 2018.)