Posters are being put up in a bid to solve a 35-year murder mystery.

On May 6, 1967, schoolboy Keith Lyon was stabbed to death on downland in Woodingdean, Brighton.

No one has ever been charged but the boy's family and Sussex Police are still hoping the crime will be solved.

A £20,000 reward is on offer for information leading to the arrest and conviction of the killer.

Police this weekend are distributing posters, printed by The Argus, across Brighton and Hove, to mark the anniversary of the 12-year-old's death.

Detective Superintendent Dave Gaylor said: "Recent appeals in The Argus and on BBC's Crimewatch programme have produced a lot of information and many people have come forward.

"The inquiry is progressing well but we are still hoping for more information for the breakthrough we need.

"We are convinced there are people out there who can help and would appeal to them to contact us.

"I refuse to believe this tragic and dreadful death does not prey on their consciences on a regular basis and I know from experience speaking to us relieves that burdon.

"It would also ease the suffering Keith's family endure daily."

The murder weapon has been lost by Sussex Police and is still being looked for. It carried traces of blood and could produce a DNA profile to identify the killer.

Mr Gaylor said even without the knife, their investigation would continue: "It does not stop us pursuing other evidence."

Keith's 84-year-old mother Valda and his brother Peter, 42, have vowed not to rest until the killer is brought to justice.

Mrs Lyon, who lives in Hove, said: "Keith's murder has ruined our lives and there is not a day that goes by when we don't think about him, what happened to him and what he might be doing now if he was alive."

Police appealed to anyone with information to contact Detective Constable Simon Cramp on 0845 6070 999.