Sunglasses trapped attacker

Duncan Turner, 44, of Sutton Coldfield, West Midlands, had earlier admitted sexually assaulting a young woman in a subway in the city.

Turner, who has a history of sex crimes dating back to 1988, was identified through pioneering DNA tests.

The father-of-two will not be eligible for parole for two-and-a-half years.

However, he will not be released if he is deemed to still be a danger to women, Judge Richard Griffith-Jones ruled at Birmingham Crown Court on Wednesday.

It must be every woman's nightmare Judge Richard Griffith-Jones

The judge praised the slightly-built victim's "courage and initiative" in recovering the sunglasses and reporting the attack, in August last year, to the police.

He told Turner: "It must be every woman's nightmare to be alone in a city walking through a subway and to be attacked by a stranger in the way that you did.

"Your actions were forceful, frightening and persistent and you only desisted because you heard the footsteps of another member of the public and you ran off in panic, leaving behind, crucially, your sunglasses."

When tested by the Forensic Science Service, the sunglasses showed Turner's DNA had been mixed together with DNA from someone else.

Scientists used a new technique called "Pendulum List Searching" which allowed them to generate a list of possible DNA profiles, which ultimately led police to Turner.