Until now, DNA left at the scene of a crime only proves useful if it is already stored in a database and can be matched to a suspect.
But a team of forensic experts have devised a way to recreate the face of a person, including eye and skin colour, using as little as 50 picograms (0.05 nanograms) of extracted DNA.
Called DNA phenotyping, the tests also determine the person’s ancestry, if they have freckles and can be used to match with distant relatives. DNA phenotyping is the prediction of physical appearance from DNA and is a technique being pioneered by Virginia-based Parabon Nanolabs.
The technology can be used to generate leads in criminal cases where there are no suspects or database hits, or to help identify remains, for example.
Samples can be potentially taken from as little as a fingerprint.
Parabon’s Snapshot Forensic system is said to be able to accurately predict genetic ancestry, eye colour, hair colour, skin colour, freckling, and face shape in individuals from any ethnic background.
Each prediction is presented with a ‘measure of confidence’.
As an example, the test can say a person has green eyes with 61 per cent confidence, green or blue with 79 per cent confidence, and that they definitely don’t have brown eyes, with 99 per cent confidence.
Based on ancestry, and other markers, the test also creates a likely facial shape.
From all of this information, it builds a computer generated e-fit.
And the test will predict how two people are related, as distant as third cousins, and great-great-great-great-grandparents.
‘DNA carries the genetic instruction set for an individual’s physical characteristics, producing the wide range of appearances among people,’ explained Parabon Nanolabs.
‘By determining how genetic information translates into physical appearance, it is possible to “reverse-engineer” DNA into a physical profile.
‘Snapshot reads tens of thousands of genetic variants from a DNA sample and uses this information to predict what an unknown person looks like.’
The project was supported with funding from the the US Department of Defense (DoD).
Ellen McRae Greytak, Parabon’s director of bioinformatics told Popular Science that the system has been used in 10 cases across the US, and the first department to release a Snapshot report was the Columbia Police Department.
It produced a profile for a ‘person of interest’ in the murder of 25-year-old Candra Alston and her daughter Malaysia Boykin in 2011.
The only piece of evidence left at the scene was an unspecified DNA sample.
here were no witnesses to the murder, so the local authorities turned to the forensic phenotyping and found the person was a male with dark-skinned, brown hair and brown eyes.
Mark Vinson, a cold case investigator with the Columbia police department, said that more than 200 people were interviewed in connection with the deaths.
Around 150 of them submitted their DNA – but none matched the sample left at the scene.
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