STRmix™, a sophisticated forensic software has been used to resolve mixed DNA (deoxyribonucleic acid) profiles previously thought to be too complex to interpret, has been used to charge suspects in two separate murder cases in Florida.
In the first case, law enforcement used STRmix™ to decipher DNA mixtures found on a firearm, clothing, and other items found in a car stolen from the Jupiter, Florida home at which the February 2017 shootings took place.
The results enabled investigators to arrest and charge second suspect, Marcus Steward with the murders of Sean Henry, Brandi El-Salhy, and Kelli Doherty.
Another individual, Christopher Vasata, previously had been arrested in the case.
(Jupiter Police announce the arrest of an additional suspect in the Jupiter triple homicide on Super Bowl Sunday. Marcus Steward, 25, is charged with three counts of first-degree murder with a firearm, one count of attempted first-degree murder with a firearm, and one count of grand theft of a motor vehicle. Courtesy of WPTV News and YouTube. Posted on Nov 28, 2017)
Use of STRmix™ in a second case enabled the Sarasota County Sheriff’s Office to charge Delmer Smith with murder and sexual battery in the April 2009 death of Georgann Lee Smith.
STRmix™ was used by DNA Labs International to interpret multiple profiles of DNA extracted from the victim’s clothes, and ultimately identify Delmer Smith’s DNA.
Smith is currently housed at Florida State Prison in Raiford after being sentenced to life in prison for armed home invasion and armed kidnapping in one Sarasota case, and sentenced to death for the first-degree murder of Kathleen Briles in a Manatee case.
Delmer Smith now will be transported back to Sarasota County to face charges in the Georgann Lee Smith case.
The two Florida murder cases are among the most recent in the U.S. to successfully use STRmix™.
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)
STRmix™ is a forensic software used by trained, experienced DNA experts to resolve mixed DNA profiles, allowing a DNA profile to be matched directly against a database.
This is a major advance for cases where there are no suspects and there is DNA from multiple contributors in one sample.
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
Furthermore, in December, evidence produced by STRmix™ was used to convict a Brooklyn, NY man of murder for slashing the throat of his estranged wife.
In that case, STRmix™ was able to isolate the defendant’s DNA in several pieces of evidence presented during the trial.
Thirty U.S. forensic labs are now routinely use STRmix™ in resolving DNA profiles.
These include federal agencies such as the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF), and the Federal Bureau of Investigation (FBI), as well as state and local agencies such as the Michigan State Police, Texas Department of Public Safety, and the California Department of Justice.
(Learn More about ESR STRmix™: Resolve More DNA Mixtures. Courtesy of KiwiNetTV and YouTube)
STRmix™, which recently celebrated its fifth anniversary of use in live casework, is also in various stages of installation, validation, and training in 56 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 launched an upgraded version of STRmix™ in mid-2017.
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