When Scott Johnson's body was found naked at the bottom of a cliff at North Head in 1988, it sparked a 29-year case that would result in two police investigations, three coronial inquests and relentless lobbying by a brother who never gave up on his fight for the truth.

State Coroner Michael Barnes today found that Mr Johnson's death was the result of a gay hate attack, and that he was either pushed or fell to his death while trying to escape.

The findings are a vindication to Steve Johnson, who, over almost three decades, has reportedly spent up to $1 million on an investigator to prove his younger brother's death was the result of foul play.

It was December 10, 1988, when Scott's naked body was found by two rock fishermen at the base of the cliff, near Blue Fish Point, just south of Manly, on Sydney's northern beaches.

Police immediately deemed the death a suicide. Furthermore, as Scott's clothes had been found neatly folded on the clifftop above, the death was considered a "ritual suicide".

Scott Johnson's clothes were found folded at the top of the cliff. ( Supplied: NSW Police )

Three months later, Coroner Derrick Hand made a formal finding that Scott took his own life.

At the inquest, police had dismissed the possibility Scott's death was somehow linked to his sexuality.

In evidence, Detective Doreen Cruickshank told the court police only became aware an area was a "gay beat" — where homosexual men would meet for casual sex — when they received reports of assault or robbery on gay people in that area and could establish a pattern.

From early on, Steve Johnson was not convinced his younger brother would kill himself.

In that first week of December 1988, Scott had every reason to be happy, having just completed his doctorate in mathematics.

Scott's former partner Michael Noone leaves an inquest hearing in June. ( AAP: Paul Miller )

Scott's boyfriend of five years, Michael Noone, was not convinced either. Following the inquest, he visited the clifftop where Scott's clothes were found and after speaking to men there, he discovered the area to be a gay beat.

But it wasn't until 2005 — following news of gay-bashing gangs and fresh coronial findings into the gay murders on the Bondi-Tamarama cliffs in the eastern suburbs in the late 1980s — that Mr Noone first suggested to Mr Johnson that Scott's death may have been the result of a gay hate crime.

This information sparked Mr Johnson to lobby strongly for the suicide finding to be set aside.

Steve looks over the cliffs at North Head in Manly. ( ABC News: Emma Alberici )

Letter from a Kennedy

The successful internet pioneer sought additional evidence that Scott's death was a gay hate crime, and lobbied powerful people to get behind his cause.

In 1989, Democratic senator Edward Kennedy wrote to NSW government figures calling for an inquest.

In 2007, Mr Johnson employed former Newsweek journalist Daniel Glick to investigate the case.

A second inquest into Scott's death was ordered, and in 2012 former deputy state coroner Carmel Forbes overturned the 1989 inquest finding of suicide.

Ms Forbes said the fact the clifftop had been a gay beat, along with information there had been a culture of violence against gay men in the late 1980s, lead her to her findings.

However, she said there was insufficient evidence to determine exactly how Scott's body came to lay at the bottom of the cliff.

She referred the case to the NSW Police cold case division, recommending that further investigation be done into all possibilities.

Mr Johnson made public appeals, and his brother's death was the subject of an Australian Story program in February 2013.

After the broadcast, then-NSW Police Minister Mike Gallacher contacted the Commander of the Homicide Squad, Michael Willing, requesting the case be reinvestigated.

Mr Gallacher also announced a $100,000 reward for anyone with information about Scott Johnson's death.

Strike Force Macnamir was formed, led by one of the State's most respected detectives, Pamela Young.

NSW Detective Chief Inspector Pamela Young speaks on Lateline. ( ABC News )

A two-year investigation by Detective Chief Inspector Young uncovered no evidence to support a finding of murder.

Young's 439-page report dismissed Steve Johnson's theory that Scott was murdered as part of an epidemic of gay hate crimes in the late 1980s and early 1990s.

The report referred extensively to the 2005 police operation Taradale, which found the deaths of three gay men in 1989 were the result of them being forced to their deaths at a gay beat on the clifftops of Bondi.

She found no evidence of similar violence against gay men at the cliffs in Manly. Instead, she agreed with the original police investigation, concluding that suicide was the most likely cause of death.

An ending, of sorts

Despite this setback, on April 13, 2015, Mr Johnson called for a fresh inquest on the basis of "new evidence".

Later that night, Detective Chief Inspector Young appeared on the ABC's Lateline program, accusing Mr Gallacher of "kowtowing" to the wealthy and influential Steve Johnson and putting pressure on police to prioritise this investigation over hundreds of other unsolved deaths.

Mr Gallacher denied those allegations.

Scott and Steve Johnson grew up in California. ( Supplied: Steve Johnson )

Fearing Young had undermined public confidence in her ability to investigate the matter impartially, Coroner Barnes dismissed her from the case, describing her television interview as "unprecedented".

In December 2016, the third coronial inquest into Scott Johnson's death began. It is thought to be only the second time in Australian history that a third inquest has been ordered in to the death of a single person.

The case of Azaria Chamberlain is the only other known case.

During the inquest the court heard that a group called the Narrabeen Skinheads bragged about assaulting an "American faggot" around the same time Scott Johnson had died.

Scott Johnson's death has been ruled a gay hate crime. ( Supplied: NSW Police )

The inquest also heard that soldiers training at the Army School of Artillery at North Head used to brag about bashing gay men and considered it "fun and games".

In handing down his findings today, Coroner Michael Barnes left one key piece of the puzzle unsolved: who was on that clifftop with Scott?

It is a question Steve Johnson wants answered.

As he told reporters outside the court that "the killers still live among us", it was clear Steve Johnson still has work to do.