Forensic experts have carried out a detailed examination of a derelict flat once occupied by a man cleared of murdering a missing schoolgirl in Northern Ireland.
Officers in white boiler suits moved into the property in the centre of Castlederg, Co Tyrone, where child killer Robert Howard lived at the time of Arlene Arkinson's disappearance 18 years ago. Police said they were not looking for human remains.
The flat in Main Street has been searched before but a forensic team was called in after serious crime branch detectives got new information, according to the Police Service of Northern Ireland (PSNI). Body recovery dogs were also brought in to help a search team check land between Castlederg and the village of Clady on the Tyrone-Donegal border.
Arlene, 15, vanished on her way home from a disco in Bundoran, Co Donegal, in August 1994. She had been seen with Howard who was acquitted of her murder in 2005 when he was aged 61.
He is currently serving a life sentence for the rape and murder of schoolgirl Hanna Williams, 14, from Deptford, south London, whose body was found in a cement works in Northfleet, Kent, in March 2002.
The flat where Howard lived when Arlene disappeared has been derelict for some time and officers had to make sure it was safe to enter before Monday's detailed forensic examination got under way.
A spokesman for the PSNI serious crime branch said: "This investigation remains active and ongoing. But it is also extremely complex and requires detectives to adopt a thorough and co-ordinated approach to progressing investigative opportunities.
"Some new information has been received. Detectives have made inquiries over the last few months to examine this information and this had led to an expansion of the existing search plan.
"The fact that new information has come into the inquiry as a result of previous appeals is heartening. Police still believe that there may be more information in the community and we would appeal for anyone with any information to come forward - for Arlene and for her family."
The spokesman said the Arkinson family had been kept up to date about the progress of the investigation. He added: "We sympathise with Arlene's family in their continued distress, frustration and anger. We maintain an absolute commitment to working to resolve their unbearable situation despite the complexities and timespan of the investigation."