A new forensic technique called Hirisplex will soon allow investigators to predict certain physical characteristics of suspects, like their hair and eye color, after analyzing traces of DNA that were left at the crime scene.
This type of testing, originated in forensic biology, is called Forensic DNA Phenotyping (FDP). FDP allows police investigators to narrow down a large group of possible suspects. The BBC reported that according to Prof, Manfred Kayser from Erasmus University Medical Center in Rotterdam, the Netherlands, who led the study, tools such as Hirisplex could be useful in those cases where the perpetrator is completely unknown to the authorities. Prof. Kayser said the test "includes the 24 currently best eye and hair color predictive DNA markers. In its design we took care that the test can cope with the challenges of forensic DNA analysis such as low amounts of materia...The test is very sensitive and produces complete results on even smaller DNA amounts than usually used for forensic DNA profiling," he added.
The test system includes the six DNA markers previously used in a test for eye color known as Irisplex, combining them with predictive markers for hair. The authors of the study used Hirisplex to predict hair color phenotypes in a sample drawn from three European populations. On average, their prediction accuracy was 69.5% for blonde hair, 78.5% for brown, 80% for red and 87.5% for black hair color.