Forensic evidence has helped many detectives, real and fictional, solve crimes. But it's benefits are limited because trace DNA left at the scene of a crime is useless unless it can be matched to samples already in a police database. A detective won't get anywhere with DNA from the lone criminal or first time offender.
But scientists have developed a new type of Forensic DNA Phenotyping that can identify perpetrators who would otherwise not be found using DNA profiling.
The technique is called HIrisPlex and it relies on 24 hair and eye color predictive DNA markers, including the 6 DNA markers developed for a DNA test for eye color called IrisPlex.
Slate's Katy Waldman writes:
"Using HIrisPlex, scientists were able to predict blonde hair with 69.5 percent accuracy, brown hair with 78.5 percent accuracy, red hair with 80 percent accuracy, and black hair with 87.5 percent accuracy. (Might the takeaway here be that blondes are more likely to get away with murder?)
"They were also able to distinguish, 86 percent of the time, between brown-eyed, black-haired people of European and non-European origin. And after analyzing DNA samples from populations around the world, they concluded that a person’s geographic ancestry did not affect the test results."
The research was published in the journal Forensic Science International: Genetics.
Lead author of the study Professor Manfred Kayser from Erasmus University Medical Center in Rotterdam, the Netherlands, tells BBC: "The test is very sensitive and produces complete results on even smaller DNA amounts than usually used for forensic DNA profiling."
Forensic DNA Phenotyping shows great promise in helping investigators narrow down suspects from a pool of individuals where there are few or no leads.
For now researchers will work on ways to improve the accuracy level of the tests.
Photo via flickr/Roger Blackwell