Lisa Dorrian: Wooded areas searched for murdered woman
Three new sites were searched on Thursday and Friday for missing Bangor woman Lisa Dorrian.
Ms Dorrian disappeared after a party at a caravan site in Ballyhalbert, County Down, in 2005. Police believe the 25-year-old shop assistant was murdered.
A fresh appeal for information about her murder was made on BBC's Crimewatch programme.
The PSNI said they searched wooded areas in Craigantlet and Carrickfergus using specially trained police dogs.
Police have pursued more than 3,500 lines of inquiry in this case and carried out almost 400 searches.
"There is nothing to suggest that Lisa came to harm at the hands of a stranger, I believe she knew her killer," Det Supt Jason Murphy said.
"Only a small number of people are aware of what happened and I believe that they may have discussed this with their friends or families in the past 13 years."
He added: "It's a case we're determined to solve.
"Allegiances change, people's lifestyles change and I want those who were with Lisa that night, or heard accounts of what happened in the immediate aftermath of her murder, or indeed over the years, to search their consciences and come forward to the police."
Lisa's sister Joanne Dorrian said the family had endured "13 years of torture".
"We lost my mum about two and a half years ago and she just couldn't cope with not having Lisa.
"She couldn't cope with the fact that she couldn't find her and lay her to rest as her first-born daughter.
"Mum died not knowing where Lisa was," she said.