California Superior Court for the County of Shasta Affirms Admissibility of STRmix

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Court rules that STRmix™ is generally accepted by the relevant scientific community and that evidence produced using STRmix™ is admissible in California v. Venegas

"STRmix™ is currently being used following laboratory validation in 58 laboratories across the United States, Australasia, and the rest of the world," ruled Judge Tamara L. Wood.

A California Superior Court has ruled that STRmix™ is generally accepted by the relevant scientific community and that evidence produced using STRmix™ is admissible in California v. Juan Manuel Venegas (#17 CR F 2383).

The defense had questioned both the admissibility of STRmix™ – a sophisticated forensic software used to resolve mixed DNA profiles previously thought to be too complex to interpret – and whether the criminologist in the case had used the correct scientific procedures in administering STRmix™.

The ruling by Judge Tamara L. Wood found that STRmix™ is generally accepted by the scientific community. Judge Wood noted, “Peer review is the process by which two anonymous referees are appointed by an editor to examine the quality of a draft scientific article … If the draft passes peer review, it will be published to the relevant scientific community. STRmix™ has been published in 47 peer review publications.”

The Court added, “STRmix™ is currently being used following laboratory validation in 58 laboratories across the United States, Australasia, and the rest of the world. These laboratories include the FBI, U.S. Army Criminal Investigation Lab, and the Colorado Bureau of Investigation.”

It also noted that the validation of STRmix™ by the California Department of Justice (DOJ) laboratory (the laboratory involved in the Venegas case) was done in accordance with the primary guidelines for probabilistic genotyping validation produced by the Scientific Working Group, DNA Analysis Methods. Those guidelines are effectively mandatory in the U.S.    

Addressing defense contentions that the DOJ’s senior criminologist, Eric Halsing, failed to follow DOJ guidelines and correct scientific procedures in administering STRmix™, Judge Wood ruled that differences between Halsing and defense expert Marc Taylor in interpreting the number of contributors to the DNA profile in question do not “demonstrate or support a conclusion that Halsing failed to follow the proper procedures, but rather go to the weight of the evidence of Halsing’s interpretation of the profiles.”

The Court concluded, “The jury is free to determine the weight to be given each expert’s opinions and the significance of the likelihood ratio results from STRmix™.”

To date, there have been at least 24 successful admissibility hearings for STRmix™ in the U.S., while DNA evidence interpreted with STRmix™ has been used successfully in numerous court cases.

A new version of STRmix™, STRmix™ v2.6, recently was introduced. The new version features a user interface that has been completely redeveloped and refreshed, providing users with vastly improved usability and workflow. Version 2.6 also enables a range of contributors to be entered when performing a deconvolution, and any type of stutter to be added and configured.

STRmix™ was developed by John Buckleton, DSc, FRSNZ, and Jo-Anne Bright of the New Zealand Institute of Environmental Science and Research (ESR), and Duncan Taylor from Forensic Science South Australia (FSSA).

For more information about STRmix™ visit http://www.strmix.com.

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Jessica Tiller
Weiss PR
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