Lynette Dawson made a decision to leave home in 1982 without taking any belongings to make it seem like her husband had killed her, a court has been told.
Giving evidence in Christopher Michael Dawson's Sydney murder trial on Monday, Paul Cooper said he had met a woman he was sure was Mrs Dawson early in 1982 at a pub in Warners Bay, on Lake Macquarie.
Cooper claimed to have struck up a conversation with the woman who said she had left her husband and children and was working up the courage to see her sister.
Telling the woman that the police might think she had been killed by her husband because had left all her belongings, Cooper said he was shocked by the response.
"When I looked back at her, she had a different demeanour at that time and it shocked me because I thought that might have been the intent," he told Justice Ian Harrison.
Cooper claimed the woman was waiting for a passport and was planning to fly first to Bali and then onto another overseas country. She allegedly asked Cooper to book a motel for her because she had no identification.
After seeing a report on Mrs Dawson on A Current Affair three years ago, Cooper said he contacted Dawson's lawyer Greg Walsh. He told the court he didn't contact the police, fearing they would be biased.
Under cross-examination by crown prosecutor Craig Everson SC, Cooper admitted that he had spent time in prison for drugs, armed robbery, theft, and break and enter.
He couldn't remember if he had actually asked the woman's name on the day, and said he was sure she wasn't wearing glasses at the time.
Despite Cooper claiming the woman said her sister lived near Warners Bay, Mr Everson pointed out that Mrs Dawson's actual sister, Pat Jenkins, lived a three-and-a-half hour drive away in the town of Stuarts Point.
Also on Monday, Justice Harrison dismissed evidence that Dawson sought out someone to get rid of his wife seven years before she vanished.
Last month, Robert Silkman claimed Dawson approached him on a busy plane flight from the Gold Coast to Sydney to ask if he knew someone who could get rid of Mrs Dawson.
Silkman's evidence was put forward to show that Dawson had specific tendencies that pointed to the murder of his wife.
Dawson's legal team attacked Silkman's credibility, pointing out that he had frequently lied to police and the courts, and had spent time in jail for theft and arson.
His evidence was rejected alongside testimony of three other witnesses Judith Solomon, KF and Roslyn McLoughlin who claimed they saw Mrs Dawson with black eyes or bruises before she disappeared in January 1982.
This evidence did not have significant probative value, the judge said.
The trial continues.
