The elderly couple arrested on suspicion of murdering their son are working with a former detective on a TV documentary about the case.
Charles and Doris Clark are helping Mark Williams-Thomas while under investigation in connection with the death of their son Steven.
The 23-year-old mysteriously vanished on December 28, 1992, after going into a public toilet in Saltburn, North Yorks, while his mum was in the ladies.
Doris, 82, was spotted filming last month close to the spot where Steven went missing.
Both she and husband Charles, 78, were due to answer bail on Sunday but were released under investigation by Cleveland Police after their arrest in September.
They deny any wrongdoing and are trying to solve the mystery of their son’s disappearance.
Mr Clark, like his wife a former police officer, confirmed they agreed to do an ITV documentary.
He said: “We have no evidence at all of Steven being dead.
“I think he is alive – so let’s look for him.
“He went for a walk on the beach and was then seen two or three days later by a lot of people.
He was alive in Redcar days later, from the police statements (at the time).”
Asked if he thought it was unusual to film a TV documentary while under investigation for murder, he laughed, adding: “We did not seek legal advice at all.
“We are looking for Steven.
“He is missing.
They are putting a TV documentary together to find him, and I don’t know any more than that.”
ITV and Mr Williams-Thomas were approached for comment.
The Clarks still live in the home in Marske-by-the-Sea – three miles from Saltburn – which they shared with their son.
A mystery letter writer who named Steven’s “killer’” in a 1999 message to police came forward after the Mirror published extracts for the first time last month.
One witness has come forward to say that she saw him close to his family home, two hours after he was reported missing.
Steven was described as having a “distinctive” gait after a car accident had left him with a limp.