How science snared the Strangler
The groundbreaking DNA profiling method being used in the hunt for Emma’s killer is the same technique US scientists used to identify the Boston Strangler more than 50 years after his crimes.
The Y-STR method was only introduced by the Scottish Police Authority Forensic Services six months ago.
It has been used to great effect in the US and in 2013 confirmed the identity of the notorious strangler believed to have murdered 13 women in the 60s.
Forensic experts obtained a near-certain match with Albert DeSalvo – the man who confessed to the murders of 11 Boston women, and two more, but was never prosecuted for the crimes.
Scientists matched DNA taken from the body of 19-yearold Mary Sullivan, who was raped and murdered 50 years ago, to the suspected killer.
Authorities told how the technique allowed them to test DNA from the scene of Mary’s death and get a match first with DeSalvo’s nephew and later with his exhumed remains – excluding 99.9 per cent of suspects.
Last year, police in the US used the same profiling method to close the case of missing 17-yearold Michael Perdue more than 30 years after he disappeared.
The method was first used in the UK in 2008.
Amanda Pirie, of the Scottish Police Authority Forensic Services, said: “In cases where the victim is female and the suspect is male, Y-STR DNA profiling can help.
“The test is called Y-STR as it profiles DNA only from the Y-chromosome, which is found only in males.
“This sensitive technique will detect even very small amounts of male DNA but ‘ignores’ any female DNA because, unlike the regular test, it does not detect DNA from other chromosomes.”