Court to rule on cliff murder admission

He later told his confused lawyers "I didn't do it but I'm saying I'm doing it ... it's the only way, she's going to come after me" - suggesting his former wife would attack him.

White also pointed to stress including seeing the victim's brother Steve Johnson and police in court.

His guilty plea - and whether it was in the interests of justice to permit him to reverse it - was the subject of the two-day hearing in the NSW Court of Criminal Appeal in October.

Chief Justice Andrew Bell and Justices Natalie Adams and Richard Button are due to deliver their decision on Friday.

White's barrister submitted the cognitively impaired prisoner didn't have the requisite knowledge to make an informed plea, given technicalities in the case including liability.

But the prosecution said it was "very significant" that White told his lawyers "this is not a split (sic) decision ... I have been thinking about this".

The American mathematician's death was initially ruled a suicide, but a coroner in 2017 determined it involved human intervention, leading to White's arrest in 2020.

After a judge refused to allow White to reverse his plea, the 52-year-old was sentenced to at least eight years and three months in jail.

While not finding it was a gay hate crime, she said White had reckless indifference to Dr Johnson's life when he threw a punch near the unguarded edge of a high cliff and fled without notifying police he had disappeared over the edge.

Steve Johnson, who flew to Australia for the appeal, later said he was disappointed his brother's case was "still not settled".

But he could see the importance of ensuring White's plea and subsequent conviction was sound.

"Even though it was gruelling, seeing the care that has been taken to be sure that the defendant is well treated, I respected that," Mr Johnson said.

"If it turns out that his guilty plea is overturned, then I'll live with what follows after that - even if it's a trial."