Ashleigh Hall was found dead in a field near Sedgefield in October
Detectives have appealed to the public for help in tracing a laptop belonging to a man accused of killing a County Durham teenager.
The body of 17-year-old Ashleigh Hall was discovered in a field near Sedgefield on 26 October.
Peter Chapman, 32, has been charged with murder, kidnap and rape. He denies all the charges.
Police believe he once owned a black Acer laptop, which is now thought to be in the Darlington area.
It is thought that following Ashleigh's death it ended up on Teesside, and was sold from a house in the Marton Road area of Middlesbrough on 24 November.
Det Con Robbie Rodiss, of Durham Constabulary's Major Crime Team, said: "We know the person who bought the laptop lives in the Darlington area.
"We know he was driving a van and that he may be employed as a roofer.
"Sadly, despite appeals in the media and our own investigations we have not been able to trace that person."
Ashleigh, of Warwick Square, Darlington, was found dead in a farmer's field close to the Little Chef roundabout, off the A689 and A177 roads, near Sedgefield.
Mr Chapman, of no fixed address, is due to go on trial at Teesside Crown Court on 8 March.