The murder case of two 11-year-old boys beaten and buried alive 36 years ago has been reopened after new evidence emerged.
John Greenwood and Gary Miller were found hidden under a mattress on a rubbish tip in Whiston, Merseyside, on 16 August 1980.
The best friends were discovered by dog walkers and later died in hospital of head injuries.
A 20-year-old man "described as having a mental age of ten" was charged and tried for their murders but was found not guilty in 1981.
The confession he made to police was discredited during the trial because it had not been witnessed by a lawyer or guardian.
Merseyside Police now hope to speak to anyone who "may have seen a man with three young boys, aged between 12 and 14 years, near to the church hall on Dragon Lane, Whiston, between 18.45 BST and 19.20 BST on Saturday 16 August 1980."
Det Ch St Paul Richardson added: "Two of the boys who were seen with the man were stood on the wall of the church hall and one was in the grounds of the church hall. Were you one of the three boys?"
John's sister Deborah Lewis, 38, from Whiston, described the original investigation as "very flawed".
She welcomed the news the case is being reopened and said: "We tried over the years to get the police to do more and it's very frustrating."
Speaking on behalf of the two families, she urged "those who know the truth to speak up".