USING crime-scene DNA to paint a picture of a suspect, rather than to find an exact match, could become more common police practice. So say researchers who predicted the ethnicity of a suspect in the 2004 Madrid train bombings in Spain from a DNA sample found on a toothbrush.
To settle controversy over whether Basque separatists were involved, a judge later ordered investigators to determine whether DNA recovered in the flat of the suspected bombers came from north Africans or Europeans. From single-letter variations in the DNA, Christopher Phillips at the in north-west Spain concluded that DNA on a toothbrush found in the flat belonged to a north African (PLoS ONE, ). The DNA was later confirmed as coming from an Algerian, Daoud Ouhnane, by conventional comparison with DNA from one of his relatives.
Such DNA profiling could help police by ruling out some suspects early in an investigation, Phillips says, though he warns that it could also alienate people from ethnic groups who might feel unfairly targeted. 鈥淚 don鈥檛 think it鈥檚 going to be mainstream for a while,鈥� he says.
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It isn鈥檛 just ancestry that can be predicted from unmatched DNA. Researchers can already predict some shades of eye and hair colour with reasonable accuracy, while work is under way on facial proportions.