Detectives investigating the murder or missing teenager Arlene Arkinson have searched a flat in Castlederg, County Tyrone.
It's understood the flat, on Main Street, is the former home of child killer Robert Howard who was acquitted of her murder in 2005.
Police have said it is a detailed forensic examination, not a search for human remains.
Arlene, 15, disappeared in August 1994 after a night out in County Donegal.
Police Service of Northern Ireland Assistant Chief Constable Drew Harris said they were acting on new information.
"This remains a live murder investigation," he said.
"On the back of this information we have decided to re-examine premises in Castllederg and this will involve a full forensic search of them.
"New forensic methods allow more to be done than could be done in 1994."
ACC Harris said this was not the first time the PSNI had visited the flat.
"The premises have previously been searched but we feel there is value in going back because of the advances in forensic science over the years.
"We have also recommenced the search for Arlene Arkinson's remains in the wider Castlederg area and a different team involving specialist officers and search dogs is involved in that piece of work at multiple sites."