Detectives probing the murder of a County Durham woman in 1996 have made an inch-by-inch search of a garden.
Julie Smailes had been strangled and stabbed
Julie Smailes, 27, was strangled and stabbed at her home in Leadgate, near Consett.
In April, police said forensic evidence now placed John Thompson, 27, at the scene of her death. He hanged himself 10 months later.
Police said the search was centred on the house of a woman found dead in mysterious circumstances in 1999.
Miss Smailes was found dead in her smoke-filled house. She had been repeatedly stabbed, and strangled.
Shortly after 0800 BST on Wednesday, a specialist search team with metal detectors moved into the back garden of a semi-detached house in Delves Lane, Consett.
Durham Police say the latest development is the direct result of new information following a public appeal by Miss Smailes' mother Joy Gilmour in April.
A force spokesman confirmed the search was at the former home of Emma Kennedy, 28, whose battered body was found at the foot of the 180ft Hownsgill Viaduct on New Year's Eve, 1999.
While an inquest returned an open verdict on her death, her family claimed she was murdered.
Durham Police have confirmed that Miss Kennedy was known to John Thompson, named as being involved in the murder of Julie Smailes.
But the force spokesman said there was no connection as yet between the murder of Julie Smailes and the death of Emma Kennedy.
Detective Superintendent Harry Stephenson said: "While I feel certain Thompson was there when Julie died, I have long been convinced he was not alone.
"There may have been as many as four people in the house.
"We won't rest until all avenues of inquiry are exhausted or those responsible have been arrested and dealt with by the courts.
"But I think it is extremely important to point out the householder whose back garden we are digging up is not implicated in any way with Julie's death.
"The current householder is cooperating fully."
Mr Stephenson said he also hoped a new series of laboratory tests which are being carried out by forensic experts would provide further clues.
He said: "The appeal by Julie's mum has, during the last few weeks, brought forward a number of new witnesses and new information that could prove crucial.
"We also intend in the very near future to revisit a number of key witnesses we have already interviewed who may now be able to provide us with further help."