Police told to open 'gay hate' murder case

Police have been ordered to look again at the case of gay American Scott Johnson, who was found dead below cliffs in Sydney's north.

Detectives have been ordered to reopen an investigation into the death of a gay American maths genius found dead at the bottom of cliffs near Sydney's northern beaches.

Scott Russell Johnson's crumpled naked corpse was found by spear fishermen at the foot of cliffs just north of Blue Fish Point, at Manly's North Head, in December 1988.

The spot is a well-known gay "beat", and the 27-year-old former NASA staffer's belongings were discovered 10 metres back from the cliff edge.

A March 1989 coronial inquest recorded a verdict of suicide.

But a raft of fresh evidence has raised the possibility Mr Johnson was murdered as part of a "gay hate" killing spree aimed at homosexual men in Sydney during the late 1980s.

Those deaths, involving men being forced to their deaths from cliffs near Bondi, were revealed to be murders only after a 2005 police investigation, Operation Taradale.

The inquest into Mr Johnson's death was reopened in Sydney on Wednesday, and NSW Deputy State Coroner Carmel Forbes recorded an open verdict.

She ordered cold case detectives immediately re-examine the case.

"The possibilities that Mr Johnson was the victim of a gay hate crime similar to those that occurred in Bondi, or that he fell, are also available explanations," she told Glebe Coroner's Court.

The case was reopened partly thanks to the work of an investigative journalist employed by Mr Johnson's wealthy brother, Steve, a Boston-based internet entrepreneur.

Reporter Daniel Glick began examining the case in 2007 and travelled to Sydney dozens of times to interview potential witnesses and chase up leads that Mr Johnson's family believe police failed to investigate.

The Johnson family then passed a large cache of documents to NSW Police, who began looking at the case again.

Detective Senior Constable Timothy Wilson, who became involved in 2011, told Wednesday's reopened inquest that he had since ruled out suicide as a cause of death.

"I can't distinguish between misadventure or homicide," he told the court.

He said the case had distinct similarities with the deaths of several gay men who were forced from cliffs near Bondi during the late 1980s.

There were also up to 10 more deaths at Sydney beaches involving gay men in the years around Mr Johnson's death, the inquest heard.

Steve Johnson said he was thrilled by Wednesday's findings.

"We're incredibly happy with the outcome," he told AAP.

"For 23 years we've had a question mark hanging over why he died. Hopefully, now we can get some answers."

Scott Johnson had a superb academic pedigree, having studied at Cambridge University in the UK and collaborated with professors at Harvard in the US.

He had also worked at NASA's jet propulsion laboratory and was about to earn a maths PhD from the Australian National University in Canberra.