* Scientists uncover new field of research that could benefit crime scene forensics *

A team of investigators led by scientists at the Translational Genomics Research Institute (TGen) has found a way to identify possible suspects at crime scenes using only a small amount of DNA, even if it is mixed with hundreds of other genetic fingerprints. Using genotyping microarrays, the scientists were able to identify an individual’s DNA from within a mix of DNA samples, even if that individual represented less than 0.1 percent of the total mix. They were able to do this even when the mix of DNA included more than 200 individual DNA samples. The results appear August 29th in the open-access journal PLoS Genetics.

The discovery could help police investigators better identify possible suspects, even when dozens of people over time have been at a crime scene. It also could help reassess previous crime scene evidence, and it could have other uses in various genetic studies and in statistical analysis.

“This is a potentially revolutionary advance in the field of forensics,” said the paper’s senior author, Dr. David W. Craig, associate director of TGen’s Neurogenomics Division, which is otherwise charged with finding ways to treat diseases and conditions of the brain and nervous system. “By employing the powers of genomic technology, it is now possible to know with near certainty that a particular individual was at a particular location, even with only trace amounts of DNA and even if dozens or even hundreds of others were there, too.”

Currently, it is difficult for police forensic investigators to detect an individual if their genomic DNA is less than 10 percent of a mix, or if it is from a large mix of DNA material. A long-held assumption within the field of forensic science – now being overturned – was that it was not possible to identify individuals using pooled data.

According to Commander Brent Vermeer, director of the Phoenix Police Department crime lab, much DNA evidence is rendered useless because of contamination, and that to eventually put the TGen theoretical research into a cost-effective police practice “would be an amazing asset.”

A new Arizona law, Senate Bill 1412, passed in June by the Legislature, requires police agencies to keep DNA evidence in cases of homicide or felony sexual assault for as long as convicts are in prison or on supervised release, or at least 55 years in unsolved cases. Some like Phoenix keep it indefinitely.

“As technology advances, we need to be prepared to keep evidence that, down the road, could prove again to be useful,” said Vermeer, who heads a bureau of nearly 130 analysts and crime scene investigators.

Dr. Stanley F. Nelson, director of the UCLA site of the National Institute of Health’s Neuroscience Microarray Consortium, said forensics investigators are “often stymied” because they now search for fewer than 20 DNA markers. The TGen researchers looked at hundreds of thousands of markers to make their identifications, he said.