A Sydney man has been jailed for more than 12 years three decades after murdering an American mathematician at a Sydney gay beat.
The jail sentence was handed down on Tuesday by Justice Helen Wilson who found that in a hostile act, Scott White had punched Scott Johnson at North Head in Manly in December 1988, causing him to fall to his death.
"[White] did a violent act and that act is the direct cause of Dr Johnson leaving the clifftop in terror," the judge said.
With reckless indifference to human life, White threw the punch near the unguarded edge of the high cliff and then fled without notifying police that Dr Johnson disappeared over the edge.
Dr Johnson worked for NASA's Jet Propulsion Laboratory mapping the surface of Venus before moving to Australia in May 1986. He was working at the Australian National University at the time of his death.
White has been sentenced to 12 years and seven months in jail, and will be eligible for parole after eight years and three months.
Justice Wilson found there was not enough evidence to show the murder was a gay hate crime, however, because White had met Dr Johnson at the Brighton Hotel and the pair had willingly gone to the gay beat together.
White received a discounted sentence because of his past. As well as being forced to fight for his alcoholic parents' amusement and living on the streets from 14 years while addicted to alcohol, White, who himself is gay, lived with a homophobic family.
"Being gay was [White's] biggest secret because his brother and his family hated gays," the judge said.
The sentence also reflected the more lenient murder sentences of the late 1980s and early 1990s, White's younger age of 18 when the crime was committed, and his then intellectual impairments.
Justice Wilson acknowledged the unbearable pain felt by Dr Johnson's loved ones such as brother Steve Johnson and partner Michael Noone had felt because of his death and their more than 33-year fight for justice.
"The court can and does extend every sympathy to Mr Johnson and his family and Mr Noone and his family," she said.
The outcome ends a long-running ordeal for Dr Johnson's family who refused to believe an initial inquest finding of suicide.
Speaking to reporters outside court, Steve Johnson was thankful for the efforts of the crown prosecutors, the court system and the Australian public who ensured White had finally been sentenced to jail.
"We didn't get compensation for Scott this week but what Scott got was dignity," he said.
Mr Johnson said he had no second thoughts about chasing the case for three decades, and hoped the outcome would bring about greater change and further arrests for gay bashings of the 1980s.
He also thanked White for paying attention to the Johnson family and what they had to say during a sentence hearing on Monday.
"During all of our statements, he kept eye contact. He didn't shake his head and he didn't shirk. He really seemed eager to hear what we had to say and I really appreciate that."
An appeal of White's conviction has already been filed after his defence team failed to overturn a guilty plea in January.
After the initial 1989 inquest finding, the case was reopened in 2012. Another inquest returned an open finding in 2012, but a third in 2017 found Dr Johnson fell from Manly's North Head clifftops because of violence by an unidentified attacker who perceived him to be gay.