STRmix– sophisticated forensic software used to resolve mixed DNA profiles previously thought to be too complex to interpret– has been ruled admissible in two recent Colorado court cases.
In People v. William Tyrel Korn (Case No. 18CR84), the Colorado District Court for Garfield County ruled that STRmix has been “… repeatedly tested and subjected to peer review and publication,” “… generally accepted in the scientific and forensic community,” and “… internally validated for use in over 40 labs in the United States, including the FBI and the Colorado Bureau of Investigation.”
The court ultimately denied defendant’s motion for a Shreck Hearing, noting that probabilistic genotyping evidence using STRmix software “satisfies the requirements for relevance and reliability” under People v. Shreck (No. 02CA1413). In that 2001 case, the Colorado Court of Appeals determined that before expert testimony may be admitted, a trial court must be satisfied that the scientific or specialized principles underlying the testimony are reasonably reliable; the expert is qualified to opine on such matters; and the expert testimony will be helpful to the jury.
In the second case, People v. Edward Aragon (No. 2015CR147), the Colorado District Court for Otero County held a pre-trial Shreck Hearing, and concluded “… the scientific principles underpinning STRmix are reliable.”
Disagreeing with the defendant’s claim that the prejudicial effect of the evidence generated by the use of STRmix would substantially outweigh its probative value, the court concluded that DNA profiles developed through the use of STRmix “… will be useful to the jury on the issue of identity, and that the probative value of this evidence is not substantially outweighed by the danger of unfair prejudice.”
The two Colorado decisions bring the number of successful U.S. admissibility hearings regarding STRmix to 30. Since its introduction in 2012, STRmix has been used to interpret DNA evidence in more than 120,000 cases worldwide, including numerous U.S. cases.
Forty-nine U.S. forensic labs now routinely use STRmix to resolve DNA profiles, including the FBI, the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF), and multiple state and local agencies. STRmix is also in various stages of installation, validation, and training in more than 60 other U.S. labs.
“Forensic labs are turning to STRmix because it has greatly improved their ability to produce usable DNA evidence in a wide range of criminal cases,” says John Buckleton DSc, FRSNZ, Forensic Scientist at the New Zealand Institute of Environmental Science and Research (ESR) who developed STRmix in conjunction with Jo-Anne Bright, also with ESR, and Duncan Taylor from Forensic Science South Australia (FSSA).
According to Buckleton, agencies using STRmix are reporting an increase of interpretable DNA in gun cases alone from about 40% to more than 70%. STRmix is also proving to be highly effective in sexual assault cases.
A new version of STRmix, STRmix v2.7, was introduced in September. STRmix v2.7 includes several new features in direct response to recommendations for improvements made by forensic labs to better address the on-the-job needs they regularly encounter. DBLR™, an application used with STRmix, was also introduced earlier this year. DBLR allows users to undertake superfast database searches, visualize the value of their DNA mixture evidence, and carry out mixture to mixture matches.
In addition, an updated STRmix Defense Access Policy gives defense legal teams even easier access to STRmix software. The updated Access Policy includes definitions of the extended items that can be provided under the policy, updated non-disclosure agreements (NDAs), and an abbreviated NDA for use in some specific circumstances.