Gary James Mitchell was traced from DNA evidence dating back to 1979

Gary James Mitchell, 41, who is already serving a 10-year sentence for rape, was traced by Northumbria Police officers through Operation Phoenix.

This uses modern forensic techniques to re-investigate unsolved sex crimes.

It found evidence linking Mitchell to an incident in Felling, Gateshead, in 1979 in which a woman was raped, but no-one was arrested at the time.

Mitchell, originally from Felling, was arrested in 2000 on suspicion of a burglary in Hexham, as a result of which he gave a sample for DNA profiling.

There is no doubt that Northumbria is a safer place as a result of Mitchell being put behind bars for life Detective Inspector Garry Dixon

This was found to be an exact match for a sample taken from a rape scene in Chester-le-Street, in County Durham, in 1995.

Mitchell was convicted and sentenced to 10 years, by Newcastle Crown Court.

In 2003, Operation Phoenix was able to link him to an incident in Birtley in 1987 in which a woman was grabbed at knifepoint, dragged on to waste ground and raped.

Mitchell pleaded not guilty, but was convicted by the court.

Evidence also linked him to the 1979 rape to which he pleaded guilty on Monday.

Sentencing for both rapes took place on Wednesday when Mitchell was given a life sentence.

Detective Inspector Garry Dixon of Northumbria Police said: "There is no doubt that Northumbria is a safer place as a result of Mitchell being put behind bars for life.

"He is a serial rapist and our inquiries will continue to consider whether he can be linked to other undetected offences."

He also praised the victims for being prepared to undergo a re-investigation of the original offences, and for co-operating with the police.