A witness has claimed he met Lynette Dawson at a NSW hotel in early 1982, during which she confided her plan to run away overseas.
Chris Dawson is standing trial in the NSW Supreme Court, where he has pleaded not guilty to murdering his wife who disappeared from their Bayview home on Sydney's northern beaches in January 1982.
Mr Dawson's defence has argued that she fled their marital home of her own volition and had contacted her husband by phone several times after she had left.
The Crown prosecution alleges that Ms Dawson was killed by Mr Dawson so that he could be with a then teenage former student and babysitter, JC.
The defence called Paul Cooper, a man who said he had a chance meeting with Ms Dawson at a pub at Warners Bay, in the Lake Macquarie region, in early 1982.
Mr Cooper, 60, told the court that Ms Dawson looked out of place given the hotel was a "tradie's bar".
Mr Cooper, from the Gold Coast, told the court that the woman told him that she had fled her home because her husband had been unfaithful, that he was "controlling" and she was leaving to start another life.
Mr Cooper said she asked him to book a motel room for her because she didn't like where she was staying at the time.
"Apparently, the gentleman who owned the place where she was staying had been coming into her room and making advances and she didn't like it," Mr Cooper said.
Mr Cooper said Ms Dawson had told him that she had two children but was running away from her family home because of marital problems.
"We got back to the reason why she wanted me to book (the motel room) was because she didn't have any ID on her at all," Mr Cooper told the court today .
"She had money because she sold something and she'd been planning it for a couple of weeks.
"She didn't have it quite all together. She was waiting to get a passport from somebody who was going to meet her in a couple of weeks, she had to wait two weeks to get a passport … She was going to go to Bali and then head off to another country overseas."
He said he tried to convince her to not leave her young children, having grown up without his own parents.
He also told her that by leaving people would presume that Mr Dawson had murdered her.
But Mr Cooper said he formed a view that it was the woman's intention to set "her husband up".
"I said to her they're going to think he knocked ya," Mr Cooper said.
"And I got the impression that was the whole process of it, leaving everything behind. I was taken aback by it."
He said he had never been in contact with Mr Dawson but saw an image of Ms Dawson on A Current Affair in 2018.
He said he did not go to the police because he doubted they would believe him and instead contacted Mr Dawson's solicitor Greg Walsh.
"How do you know the woman in 1982 at the Warners Bay Hotel was in fact Lynette Dawson?" he was asked by defence barrister Pauline David.
"Just her smile and the presence of her face. It's sort of a sad image, it made an impression on me," Mr Cooper said.
"It was an unforgettable afternoon, it blew me away. I've never been able to forget it."
Mr Cooper added that he was "100 per cent" certain that the woman he spoke to in the hotel was Ms Dawson.
Under cross-examination from Crown prosecutor Craig Everson, Mr Cooper told the court that he had been to jail for theft, drug offences, breaking and entering and armed robbery.
The court was told that he had been arrested for possession of marijuana and heroin.
However, he denied his use of those drugs had affected his memory.
The defence closed its case yesterday afternoon after calling Mr Cooper.
The trial continues with closing submissions.