Scientists have developed a forensic test that can predict both the hair color and the eyes of a potential suspect, using DNA left at the crime scene.
The team that developed the test says it can provide valuable leads in cases where the perpetrators cannot be identified by DNA profiling.
The Hirisplex the system may allow investigators to narrow down a large group of possible suspects.
Details appear in the diary Forensic Science International: Genetics.
Predicting phenotypes – external features such as hair color or eye color – from DNA information is a new field in forensics.
An important current approach, known as genetic profiling, involves comparing the crime scene DNA with that of a suspect or a profile stored in a database.
But it relies on a person who is either among a group of suspects identified by the police or has their profile in a DNA database.
Tools like Hirisplex it can be useful in cases where the perpetrator is completely unknown to the authorities, said Prof. Manfred Kaiser, who is leading the study.
He said the test “includes the 24 best predictive DNA markers for eye and hair color. In its design, we took care of the test to meet the challenges of forensic DNA analysis, such as small amounts of material. “
Prof. Manfred Kaiser from Erasmus University Medical Center in Rotterdam, the Netherlands, added: “The test is very sensitive and gives complete results for even smaller amounts of DNA than is usually used for forensic DNA profiling.”
He said the magazine article described everything needed to set up the test in a forensic lab, but that the team was also in touch with the industry about their knowledge of hair and eye color prediction.
The test system includes the six DNA markers previously used in an eye color test known as Irisplexcombining them with predictive hair markers.
In the study, the authors used Hirisplex to predict hair color phenotypes in a sample taken from three European populations.
The accuracy of their predictions was on average 69.5% for blonde hair, 78.5% for brown hair, 80% for red hair and 87.5% for black hair.
Analysis of global DNA samples suggests that the results are similar, regardless of a person’s geographical origin.
The team was also able to determine, with an accuracy of about 86%, whether the red-haired man with brown eyes was of non-European to European origin (with the exception of some nearby areas such as the Middle East).
The findings were also presented at the sixth conference of the European Academy of Forensics in The Hague this week.