STRmix™ – the sophisticated forensic software used to resolve mixed DNA profiles previously thought to be too complex to interpret – has been used in a case in which a Brooklyn, NY man was convicted of murder for slashing the throat of his estranged wife.


In its first use in a Brooklyn trial, STRmix™ assisted with the identification of the defendant’s DNA in several pieces of evidence. Evidence in the case showed that blood found inside the victim’s car, as well as on a t-shirt worn by the defendant, contained a mixture of DNA from both the victim and the defendant.


According to testimony in the trial, the victim, Karen Ashley, was found dead in her car in September 2016. Police said Ms. Ashley’s throat had been cut. She also suffered multiple knife wounds to her body.


Ms. Ashley’s common-law husband, Beresford Ashley, turned himself into police shortly after the incident. He told police that he had been in an argument with his wife and may have committed an offense. At the time of his arrest, Mr. Ashley had a cut on his hand and the t-shirt he was wearing had blood on it.


Mr. Ashley was convicted of second-degree murder and fourth-degree criminal possession of a weapon. He faces 25 years to life in prison.


STRmix™ has now been used successfully in a number of U.S. court cases, as well as thousands of cases internationally. There have also been at least 13 successful admissibility hearings in the U.S. for STRmix™.


Thirty U.S. labs now routinely use STRmix™ in resolving DNA profiles. This includes everything from federal agencies such as the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) and the FBI to state and local agencies, including the Michigan State Police, Texas Department of Public Safety, and the California Department of Justice.


STRmix™, which recently celebrated its fifth anniversary of use in live casework, is also in various stages of installation, validation, and training in 51 other U.S. labs.


“In five short years, STRmix™ has moved from being an experimental technology to the broadly accepted norm in cases in which a sophisticated forensic 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). Buckleton developed STRmix™ in collaboration with ESR’s Jo-Anne Bright and Duncan Taylor from Forensic Science South Australia (FSSA).


ESR recently launched an upgraded version of STRmix™ after a full year of technical development and testing. STRmix™ v2.5 contains a number of new features designed to improve functionality, speed, memory, and ease of use, including: multi-kit functionality, enabling interpretation of DNA profiles from different test kits; a likelihood ratio (LR) batcher tool, allowing users to calculate multiple LRs from multiple reference inputs to a previously run deconvolution; and a combined DNA Index System (CODIS) report.

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