There have been renewed appeals for information about the missing body of Lisa Dorrian (25) on the first anniversary of her disapperance.
Ms Dorrian, who is presumed murdered, was last seen in a caravan park in Ballyhalbert, Co Down, where she had been at a party.
Joanne Dorrian sister of muder victim Lisa Dorrian: 'I would like to think they have a conscience, but all I can say is it's going to be a hell of a lot worse for them when we find Lisa and they haven't come forward.'
The family's search for those guilty has carried on over the past year and will now be the focus of a billboard campaign aimed at triggering the conscience of those responsible or those who know what happened to the shop assistant.
On huge billboards erected across Belfast and north Down, Lisa's face smiles down beneath the message: "One year on and I'm still gone. Your conscience must be killing you."
Lisa's sister, Joanne, claims that at least six people know what happened to her, while three are suspected of alleged involvement in the killing.
"I would like to think they have a conscience, but all I can say is it's going to be a hell of a lot worse for them when we find Lisa and they haven't come forward. I see this one year anniversary as their last chance," she said.
A £10,000 reward has been offered but so far neither that nor a website where confidential information can be posted has yielded a breakthrough.
Several men have been questioned and released without charge, even though the identities of those Lisa was last seen with are known. Police believe her body may have been moved months after she was killed and dumped at sea.