A Briton sex offender admitted the kidnap, rape and murder of Ashleigh Hall, 17, whose body was found in a farmer’s field near Sedgefield last October will be serving a minimum of 35 years.

The Telegraph reports that Peter Chapman, 33, evaded police for 13 months after breaking the terms of his Sex Offenders’ Register order by failing to notify a change of address.

Chapman allegedly posted a photograph of a bare-chested, good looking boy in his late teens on Facebook to snare Ashleigh Hall.

Graham Reeds QC, prosecuting, said Chapman was obsessed with sex and was trying to meet her from the very start.

When Chapman realized that she was unlikely to go with him when she see that he was nothing like the Facebook image, he invented “Pete’s Dad” to collect her from her home which Mr Reeds described as a “calculated and wicked” plan.

Chapman picked Ashleigh up near her house and drove her to a dark and secluded lay-by on October 25 last year where he committed the crime.

Since the age of 15, he has been the subject of several sexual assault investigations, and in 1996 he was jailed for 7 years for raping two prostitutes at knifepoint.