On Friday, Dawson, now 74, was sentenced to at least 18 years in prison after killing his wife Lynette at their northern beaches Sydney home and disposing of her body in January 1982.

Justice Ian Harrison found the former teacher planned the "selfish and cynical" murder because of his obsession with a student and teenage babysitter, known as JC, and his fear he would lose her affections.

"Mr Dawson's motive to kill his wife evolved and developed in response to his desire to be exclusively with JC," the judge said in the NSW Supreme Court on Friday.

"The prospect of losing her distressed, frustrated and ultimately overwhelmed Mr Dawson to the point that he resolved to kill his wife."

The murder was "an objectively very serious crime" which was aggravated by the fact Mrs Dawson's body had never been discovered, Justice Harrison said.

The former Newtown Jets rugby league player was sentenced to 24 years in prison. He will be eligible for parole in August 2040, when he will be 92.

While an appeal has already been lodged, Dawson's solicitor Greg Walsh could not reveal any details outside court on Friday, telling reporters this would be his last day representing the convicted murderer.

Dawson will now rely on public defender Belinda Rigg SC to handle his appeal.

The challenge will likely be heard some time in 2023, although a date for a hearing in the NSW Criminal Court of Appeal has yet to be set down.

Australian Associated Press