The prime suspect in the murder of Welsh hitch-hiker Jennifer Beard has died - maintaining to the end that he had nothing to do with the three-decade-old crime.

Gordon Bray died in Timaru Hospital on Sunday. He was 83.

Miss Beard, 25, a teacher working in Tasmania, was visiting the South Island to meet her fiance, Reg Williams, and go tramping.

Her body was found under the Haast River bridge on January 19, 1970. The murder remains one of the country's most notorious unsolved crimes.

In an interview in 2001, Mr Bray, who never married, protested his innocence.

"I had nothing to do with it. The police were only doing their job I suppose," he said.

Forensic tests established Miss Beard died on December 31, 1969, but because her body had decomposed, the cause of death was never established. Police believe she was strangled in a sexually motivated attack.

She was last seen alive in a green, 1950s Vauxhall, driven by a man a witness described as being in his mid-40s, with dark brown receding hair and a pot belly.

Mr Bray was in the Haast region at the time on a fishing trip and drove a dark blue Vauxhall.

Soon after Miss Beard's body was discovered, police interviewed Mr Bray, who was working as a truck driver.

His Vauxhall was examined by forensic experts.

A year after the murder, a team of police and legal advisers rechecked the evidence but could not agree on whether to charge Mr Bray. It was decided that the evidence was insufficient to press charges.

It was a decision that inquiry head, Detective Inspector Emmett Mitten, now retired in Christchurch, still disagrees with.

"My view all along was that there was evidence to support a charge."