Former Sydney schoolteacher Chris Dawson will "probably die in jail", after being sentenced to a maximum 24 years in prison for murdering his first wife Lynette in 1982.
The 74-year-old has been in custody since he was found guilty in August, following a judge-only trial in the NSW Supreme Court.
Ms Dawson's body has never been found and the Crown argued he killed her in order to have an "unfettered relationship" with the family's teenage babysitter, JC, who he later married.
Justice Ian Harrison today said the murder was an "objectively very serious crime".
"Lynette Dawson was faultless and undeserving of her fate," the judge said in sentencing.
"Despite the deteriorating state of her marriage to Mr Dawson she was undoubtedly also completely unsuspecting."
Justice Harrison found Dawson "had a possessive infatuation" with JC, and the prospect of losing her "distressed, frustrated and overwhelmed him" to the point where he resolved to kill his wife.
He found that the fact that Lynette Dawson's body has never been located or recovered is an aggravating circumstance of the murder.
He sentenced Dawson to a maximum 24 years in prison, with a non-parole period of 18 years.
Dawson will be eligible for parole in August 2040.
During the trial, Dawson's legal team argued there was an alternative explanation for her disappearance; that she walked out on the family after her trust was broken due to his behaviour with JC.
The former rugby league player didn't give evidence, but claimed in a 1991 police interview his wife called him several times after failing to show up to a meeting at a pool in January 1982.
His lawyers also argued unverified sightings by five witnesses in the years following her disappearance showed it was possible she was still alive.
But Justice Harrison rejected those key planks of the defence case during a five-hour judgement in late August, ultimately finding it was beyond reasonable doubt Dawson's guilt was "the only rational inference" to be drawn from circumstantial evidence.
Today he acknowledged Dawson's mental and physical health issues.
"Mr Dawson is not old by contemporary standards, but the reality is he will not live to reach the end of his non-parole period, or will alternatively, by reason of his deteriorating cognitive condition and physical capacity, become seriously disabled before then even if he does," he said.
"I recognise that the unavoidable prospect is that Mr Dawson will probably die in jail."
Dawson, who wasn't charged until 2018 after a popular podcast called The Teacher's Pet examined the case, still maintains his innocence and has flagged an appeal.
Lynette Dawson's family has repeatedly called on him to "admit the truth" and reveal the location of her body so they can finally lay her to rest.
Outside of court, Lynette's brother Greg Simms said he wanted to distance his sister from her murderer.
"I would like her to be known and remembered as Lynette Joy Simms," he said.
"What we need now is to find Lyn and put her to rest. It's our time to begin living our lives without having this hanging over our heads. Chris Dawson has had 40 years of freedom. Now, it's our turn."
Outside court, Dawson's lawyer Greg Walsh said there were no winners in the tragic case and his client will, in all probability, spend the rest of his life in prison.
He said as the judge found, it was a matter of "enormous severity".
"The murder of a loving and caring mother and wife is clearly an extremely serious crime," he said.
"And His Honour has recognised that and in particular not only the loss of their life, but the impact of that loss on the direct relatives and the wider community."
Mr Walsh said Dawson maintained his innocence.
He revealed that after four-and-a-half years it will be his last day on the case, which will be handed to the senior public defender Belinda Rigg SC.
Mr Walsh said the decision was made for a variety of reasons.
"They have considerably more resources than me and she's a very, very able advocate and he will be well served with her representation."
During a sentence hearing earlier this month, Dawson's eldest daughter Shanelle told the court she had endured 41 years of "deceit, silence, trauma and gaslighting" because of him.
She questioned why Dawson didn't simply divorce Lynette Dawson and said the thought of him spending the rest of his life in jail "hurts me deeply", because she has now lost both her mother and father.
Lynette Dawson's sister, Patricia Jenkins, described his actions as "the ultimate betrayal" after he was accepted into their family.
She called him a "conniving monster" who was "hell-bent" on getting what he wanted at any cost.
