STRmix™ – Institute of Environmental Science and Research Limited (ESR)

The winner of the Prime Minister’s Science Prize is STRmix™, a software tool developed by scientists from the Institute of Environmental Science and Research Limited (ESR) in collaboration with Forensic Science South Australia (FSSA). It has been used by ESR’s forensic biology group since 2012 to help with the interpretation of DNA profiles.

One of the advantages of STRmix™ over old methods is that profiles obtained at crime scenes containing DNA from multiple persons (called mixtures) are now useful. Mixed DNA profiles can now be searched against the National DNA Profile Database directly to look for suspects in a process called mixture matching.

A distinguished international referee, commenting on the “exceptional intellectual power” needed to develop this method of DNA profiling, wrote that ” STRmix™ is truly an amazing achievement that puts New Zealand at the forefront of forensic science worldwide”.

 

 

After adoption of the STRmix™ software, ESR undertook a pilot study with two Police districts using mixture matching. Many additional profiles previously considered too complicated to interpret resulted in entries on the database and subsequently provided useful forensic intelligence to the New Zealand Police. Due to the pilot’s success, the process was rolled out to all districts later in 2013.

After the first two years of mixture matching, an additional 110 cases were matched on the database resulting in 93 hits to suspects.  It is unlikely these suspects would have been identified through DNA if it wasn’t for STRmix™.  (The average rate  overall of crime samples searched against the National DNA Database matching individuals on the database is 73%, which is one of the highest rates in the world.)

STRmix™ has resulted in a major change to the forensic science community. After being commercially released internationally in 2014, STRmix™ is now the most widely used DNA interpretation software in New Zealand, Australia, UK and North America, and its use is growing worldwide.

The development of STRmix™ is supported by over 40 publications in peer-reviewed journals, with over 420 citations. The STRmix™ team have forged collaborative relationships with pioneers in forensic science including the Federal Bureau of Investigation, the National Institute of Science and Technology (US), the US Army Criminal Investigation Laboratory, and Forensic Science South Australia.

A recent collaboration has led to the publication of a paper describing the compilation of STRmix™ validation results from 31 institutions worldwide. This is the largest collaboration of this type to date and has led to the identification of numerous offenders, leading to the solving of crimes and exoneration of innocent people.