Former Sydney teacher Chris Dawson has been found guilty of murdering his first wife, who vanished more than four decades ago.
The 74-year-old denied involvement in Lynette Dawson's disappearance from the city's northern beaches in January 1982.
During a judge-alone trial in the NSW Supreme Court, the Crown alleged he was motivated to kill Ms Dawson in order to have an "unfettered relationship" with their teenage babysitter, JC.
Dawson's lawyers argued there was an alternative explanation for the disappearance, suggesting Ms Dawson may have abandoned her family after her trust was broken.
Justice Ian Harrison on Tuesday said there was "a most compelling" body of evidence to support a rejection of that hypothesis.
Ms Dawson's body has not been found and the case against her husband was wholly circumstantial.
"Lynette Dawson had a loving relationship with her family, especially her children," he said.
"To the extent it can be reliably extracted from the observations of others, Lynette Dawson appears clearly to have adored her husband."
This suggested an "unexpected decision to leave" was "extremely unlikely", the judge said.
"She disappeared having taken nothing with her, she was without the financial means to support herself for long, or to finance her ability to ensure she was never found.
"She never contacted her relatives or friends again, she made several plans for the future that were inconsistent with an unheralded, unexpected, and voluntary disappearance."
Justice Harrison said the theory Ms Dawson abandoned her home rose no higher than "speculation, conjecture, or supposition."
Justice Harrison said after considering all of the evidence, he was satisfied Lynette Dawson was dead and that she died on or about January 8, 1982.
The judge said he was satisfied beyond reasonable doubt that Lynette Dawson died as a result of a conscious and voluntary act by Chris Dawson with the intention of causing her death.
Dawson chose not to give evidence, but previously told police his wife phoned him while he was working at a pool on January 9, 1982, to tell him she needed time away.
Justice Harrison described that evidence as "somewhat frail".
In a 1991 police interview, Dawson also claimed she made more calls to him in subsequent weeks.
The judge concluded those reported telephone calls were "lies", noting his descriptions of them had "varied over time".
"The contention that Lynette Dawson, a woman supposedly desperate to leave a relationship, would be inclined to provide telephonic updates concerning the status of her decision to leave, is simply absurd," Justice Harrison said.
"It defies common sense."
JC, who moved into the Dawsons' home and went on to marry him, told the court she was "groomed" by her former teacher and was treated like a "slave" after Lynette Dawson vanished.
She alleged Chris Dawson once told her he'd contemplated hiring a hitman to kill his wife, but reconsidered because innocent people might be hurt.
Justice Harrison said he was "not able to be satisfied" such a conversation took place, however, he otherwise found JC's evidence to be "truthful and reliable".
In his police interview, Dawson dismissed JC's hitman allegation as the product of a bitter custody dispute.
But Justice Harrison found JC's evidence was not "corrupted" or influenced by her separation.
Dawson's legal team had also highlighted alleged sightings of Lynette Dawson between 1982 and 1984 to argue it was possible she was still alive after early 1982, including working as a nurse at a Curl Curl hospital and at a royal parade.
But Justice Harrison variously rejected evidence of those sightings as "false", "a fabrication", "extremely fail" or "wholly unreliable".
He was satisfied that by some time towards the end of 1981, Dawson considered his marriage to be in "a state of incipient failure", however he was not satisfied the former teacher was also "physically violent" towards Ms Dawson.
The family of Lynette Dawson thanked supporters outside court but said there was still one last step for closure.
Her brother, Greg Simms, called for Dawson to "find it in himself" to tell them where her body is.
"The journey is not complete," he said.
"She's still missing. We still need to bring her home. We would ask Chris also to find it in himself, to be allow us to bring him home for peaceful rest.
"Finally showing some dignity, she deserves."
Chris Dawson's lawyer, Greg Walsh, has said that an appeal was "probable".
He said the elderly Dawson was "in shock" and "upset" at being found guilty of murder.
"I can confirm that it's probable of course that he will appeal against his conviction," he said.
"Mr Dawson has always asserted, and he still does, his absolute innocence of the crime of which he's been convicted.
"And he will continue to assert that innocence."
Ms Dawson's murder was the subject of popular podcast The Teacher's Pet, curated by journalist Hedley Thomas.
