Neighbours of a teenager murdered 23 years ago could unwittingly hold the key to finding her body, police have indicated.
Officers have been searching sites in Portadown, Co Armagh, since the start of last week after receiving fresh information on the possible whereabouts of Caroline Graham's remains.
At the weekend the PSNI appealed for anyone who lived or worked close to the 19-year-old's flat in 1989 to come forward.
Today the senior detective leading the investigation said he particularly wanted to hear from people who remembered what buildings were under construction or being renovated at the time.
Miss Graham was living with her boyfriend in Hanover Street in the town centre when she disappeared in April 1989.
Detective Chief Inspector Gary Crawford urged anyone who was living or working in the area of Carleton Street, Hanover Street or Church Street at the time to come forward.
Last Monday officers began searching waste ground on Carleton Street using new technology. Probes were put into the ground up to 16ft (5m) deep to determine if there were any human remains.
It was the first time the method had been used in Northern Ireland.
By Friday the search had been extended to include part of a house which was being used as business premises.
"We are making progress in terms of eliminating possible deposition sites but we need more assistance from people who lived here or worked here in 1989," said Mr Crawford.
"I would ask anyone who thinks they can help to come and speak to search teams in Carleton Street as soon as they can.
"Members of the public have come forward with information but we need more assistance if we are going to be able to return Caroline's remains to her family after all these years and progress the investigation."
The Newry woman had been living in the Portadown area for around two years before she went missing.
Police reopened the case in August and have since revealed they hold new information on the teenager's death.
One person was arrested in connection with Miss Graham's murder in 2000. But no charges were brought.
Anyone with information should contact police on 07585 22 82 83.