A £10,000 reward is being offered for help to prosecute the killer of a man in the North East 28 years ago.
Steven Clark, 23, was last seen using toilets near Saltburn pier on 28 December 1992, according to the original enquiry.
However last month Cleveland Police said a witness had seen Mr Clark later that day near his home.
Mr Clark's parents, Doris and Charles, were arrested on suspicion of his murder last month and released on bail.
Cleveland Police confirmed the bail details, but did not name the the two people arrested. However, Mr and Mrs Clark confirmed their arrest.
Mrs Clark, of Marske, said the couple "absolutely" denied murdering their son.
Crimestoppers is offering the reward for help for a conviction in the case.
A body has not been found, and cold case detectives reopened the case earlier this year.
A missing persons report said Mr Clark, from Marske, was last seen at 15:00 GMT going to the toilets at the pier after a family walk.
He was not seen coming out of the toilets and did not return home.
A witness later told police they saw Mr Clark later that day, sometime between 15:00 and 16:00 GMT.
Ruth McNee, Crimestoppers' regional manager for the North East said: "After all these years it's so sad to think that no one has come forward to say exactly what happened to this young man.
"We are hoping that someone who may have been sitting on information will now have the courage to tell us anonymously about who is responsible for Steven's unsolved death."
Mr Clark was hit by a truck when he was a child which left him with a damaged arm and leg and a pronounced limp.
He had attended the Rathbone Society in Redcar, which worked to support people with disabilities.