The author of a letter sent to police investigating a 30-year-old murder is urged to come forward to help the investigation.
Steven Clark, then 23, was last seen using toilets near Saltburn pier on 28 December 1992.
The case has been reopened and Mr Clark's parents have been arrested on suspicion of murder.
Cleveland Police said an anonymous letter was posted to Guisborough Police Station in September 1999.
Officers believe the author, who addressed it to the incident room, might have information that could help the inquiry.
'Compelled to write'
Police have not revealed the contents but said records showed the information was "assessed by officers and the information was recorded".
Det Ch Insp Shaun Page said: "They obviously felt compelled to write the letter seven years after his disappearance and I would like to hear from them again now."
The appeal to the writer comes as specialist teams begin searches in Marske where Mr Clark lived.
He had gone to use the men's public toilets while his mother went into the ladies' but was not seen coming out and did not return home.
Cleveland Police said two people arrested this week were later bailed but did not name them.
However, Doris and Charles Clark confirmed their arrest to the Press Association.
Mrs Clark, of Marske, said the couple "absolutely" denied murdering their son.