AN investigation into the murder of a gentle giant beside a lovers lane in West Lothian, five years ago, is being relaunched by detectives.

Bachelor Robert Higgins, 35, was stabbed to death and his body was found in a quarry outside Kirkliston, just a few hundred yards from the home he shared with his pensioner mother, on May 1, 1995.

Officers at Lothian and Border Police said yesterday they were relaunching the investigation in the hope of finding fresh witnesses.

The factory worker was a popular figure in Dalmeny, South Queensferry, and the community has raised more than #5000 as a reward for information leading to the identity of his killer.

The crime remains unsolved despite nationwide appeals and the bizarre discovery of the murder weapon.

Searches at the murder scene at the time failed to find the knife, but it turned up weeks later in a pensioner's kitchen.

The 71-year-old woman found it in the ground a few yards from where Mr Higgins was discovered and took it home. She had cleaned it and had been using it to chop vegetables before realising it could be connected to the killing. Any forensic clues were washed away.

Officers then turned to television show Crimewatch, and although it threw up fresh leads the search remained unsuccessful.

Two unidentified couples who were seen talking to Mr Higgins the weekend he died have still to be traced and police hope a new appeal could reveal their identities.

Detective Superintendent Ian Cowden said: ''Despite extensive inquiries and appeals at the time of the murder and in the year following, we are still seeking answers.

''We are reviewing the case and appealing for anyone who can provide information which will help us in our investigation.''

Mr Higgins' family is at a loss to explain his murder.

On the weekend he died he is thought to have gone drinking with friends after work. But he failed to come home and, uncharacteristically, did not telephone his mother, Agnes, to say he was staying out.

His family described Mr Higgins as a reliable, quiet man who enjoyed nothing more than relaxing in front of the television or having a pint with friends after a long week in the local chicken factory.

Shortly after his death, the family received two telephone calls from a woman who said she knew the killer, but police have been unable to trace her.

Mr Higgins' sister, Mrs Brenda Walker, said the family were haunted by the thought someone knew who had committed the terrible crime and was doing nothing.

She said: ''The woman said something and hung up, she gave us a name but nothing has ever come of it.

''Everyone around here is still worried, they feel the person who did this is still a danger.''

Lothian and Borders Police hope this appeal may prompt the woman to contact them directly.