A man has admitted to murdering an American mathematician three decades after his body was found at the bottom of a Manly cliff and was later linked to a string of gay-hate crimes.
Scott Phillip White had originally pleaded not guilty to murdering Scott Johnson whose body was discovered near North Head on December 10, 1988.
But on Monday during a legal argument just months out from White's trial, the 50-year-old said he was "guilty," before his defence counsel unsuccessfully sought to reverse the plea.
Supreme Court Justice Helen Wilson convicted White on Thursday and vacated his trial dates to make way for his sentence hearing instead.
The cold case was reignited with White's arrest in May 2020 after the death of 27 year old Mr Johnson was ruled a suicide at a first inquest in 1989.
Another inquest returned an open finding in June 2012, but a third in 2017 found Mr Johnson fell from the clifftops as a result of violence by an unidentified attacker who perceived him to be gay.
A $1 million reward for information was offered by police in 2018. This figure was matched by his brother Steve Johnson in March 2021.
White's arrest represented a major breakthrough for Mr Johnson's family who never stopped fighting for justice for more than 33 years.
Arresting police officers said the man was not surprised to see them when they knocked on his Lane Cove property door in Sydney's northern suburbs.
NSW Police Commissioner Mick Fuller said the $2 million was influential in the breakthrough.
"There's certainly one witness, on conviction, that would be eligible for part of the reward absolutely," Mr Fuller told reporters.
At the time Mr Fuller said it had been an "enormous journey" and the findings of coroner Michael Barnes during the third inquest were crucial to re-opening the case two years ago.
A 2018 police review of 88 suspicious deaths between 1976 and 2000 revealed 27 men were likely murdered for their homosexuality, with cases peaking in the late 1980s and early 90s.
White is due to face a sentence hearing on May 2.