Police investigating the suspected murder of a 23-year-old man in 1992 have been contacted by a witness in what has been described as a “significant” development.

Steven Clark’s elderly parents Doris and Charles Clark have been arrested on suspicion of his murder, and police have been carrying out searches of their home and garden in Marske-by-the-Sea, Cleveland.

A missing person’s report stated that at 3pm on December 28 1992, during a family walk, the son used the gents’ public toilets near the promenade in Saltburn, Cleveland, while his mother went to the ladies’.

The new witness placed Mr Clark in Marske in the late afternoon, Cleveland Police said.

When he did not come out of the toilets, Mrs Clark said she thought her son had made his own way home, but he was never seen again.

No body has ever been found.

A cold case review led detectives to suspect he had been murdered, and his parents were arrested.

Following public appeals for information, the detective leading the case said a potential witness has come forward to say she saw Steven Clark in Marske late in the afternoon.

Cleveland Police said the development gave them “significant information”.

The force said the potential witness was out with her family and reported that Steven passed them as they were walking on the High Street towards Marske square.

The man, believed to be Steven, was walking in the opposite direction towards The Ship Inn, and it had not yet got dark.

The force said the woman saw the 1992 appeal for information about Steven’s whereabouts, and confirmed with her family that it was the missing 23-year-old who they had seen, but she did not think it was relevant to the case at that time.

Detective Chief Inspector Shaun Page said: “This is an important development for us because we know that it got dark that day at around 3.45pm and this potential sighting puts Steven in Marske before that time.

“We have carried out a number of searches in the Marske area and these will be continuing.

“A lot of people knew Steven and I would again appeal for people to come forward with any information, no matter how small or insignificant they think it is.

“I would like to hear from anyone who saw Steven on Christmas bank holiday weekend in 1992, which was Friday December 24 to Monday December 27.”

Anyone with information should call 101 or Crimestoppers on 0800 555 111.

Last week the force appealed for an anonymous letter writer who contacted the force in 1999 about the case to come forward.

Mrs Clark last week denied the couple murdered their son, saying the situation was “absolutely ludicrous”.

Steven Clark walked with a pronounced limp as a result of a childhood road accident, which also left him with other disabilities.

At the time he disappeared, Mr Clark attended the Rathbone Society in Redcar, which worked with people with disabilities to improve their employment skills, and he had won the Apprentice of the Year Award.