'Dream' software boosts power of DNA

By Andrew Koubaridis

The ESR technology has caught the attention of forensics experts in the United States. Photo / Dean Purcell
The ESR technology has caught the attention of forensics experts in the United States. Photo / Dean Purcell

The new software, called STRmix, has the ability to unscramble DNA found at crime scenes from up to four people - giving results that were previously not possible.

It has already caught the attention of the United States Army, which sent a team of people to Auckland for a workshop at the Environmental Science and Research (ESR) Mt Albert laboratory to learn more about the software, with a possibility of purchasing it. The California Department of Justice has also shown interest.

"It solved a major problem in DNA analysis by allowing an interpretation of evidence that previously wasn't interpretable, therefore increasing the power of DNA quite markedly," ESR principal scientist Dr John Buckleton said.

Dr Buckleton said that was most evident in two places. "Our ability to search mixed strains against the database. We've previously not been searching complex mixtures against the database - and now we can - and we've already run a trial."

The other was in major crime, where more complex cases were being worked much more often. "I'm guessing [there will be] a 30 per cent improvement in the power of DNA."

He told the Herald what was now a reality had been dreamed about by scientists for many years.

STRmix was developed by Dr Buckleton and Jo Bright over two years in partnership with a forensic scientist from South Australia, Dr Duncan Taylor. It works by applying a combination of mathematical modelling and DNA interpretation methods.

He was hoping other agencies around the world would purchase STRmix. "A significant fraction of the world will be on it soon, that's the hope."

STRmix is already being implemented in New Zealand and across Australia.

How it could work

Following a series of suspicious fires, a shopping bag is found at one of the scenes. The handles of the bag are swabbed for DNA analysis, resulting in a low level, mixed DNA profile of two people. A reference sample is supplied from a suspect. STRmix is used to interpret the mixture and the results support the proposition that the DNA originated from the suspect and one other person, with a reported likelihood ratio of at least 10 thousand million million (1x10 to the power of 16). Technology developed by New Zealand scientists means new DNA testing can deliver results that until now were considered a "dream" by forensic experts.

- NZ Herald

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