Chris Dawson allegedly left bruises on his wife's neck and said he would be "getting rid" of her if their marriage counselling didn't work, a Sydney court has heard.
Mr Dawson, a former school teacher on Sydney's northern beaches, is accused of murdering his wife Lynette in 1982 so he could have an "unfettered relationship" with the couple's then-teenage babysitter.
The 73-year-old has pleaded not guilty.
On Monday, Annette Leary, who worked with Ms Dawson at the Warriewood Children's Centre in the early 1980s, told the court she had noticed bruises on her colleague's throat just days before she disappeared.
Giving evidence from her home via audio-visual link, Ms Leary was asked if Ms Dawson ever spoke to her about her husband.
"Only she said they were having a little trouble in their marriage and she had talked Chris into going to a marriage counsellor with her to see if they could resolve it," she told the court.
"One day when I came into work, she had bruises on her throat."
The witness told the court she then proceeded to ask Ms Dawson what had happened.
"She said when they went to counselling, [they] got in the lift and Chris had gripped her throat and shook her a little and said, 'if this doesn't work, I'm getting rid of you, I'm only doing this once'."
The witness told the court Ms Dawson didn't believe her husband was being serious.
The Crown then asked the witness if she had seen Ms Dawson after they had had this conversation.
"No, in fact when I came to work — they called me in on the Monday — the director said Lynette hadn't come into work," she said.
"She hadn't rung to say anything, or call in sick."
Ms Leary will resume giving evidence on Tuesday.
The court also heard from Ms Dawson's manager at the childcare centre, Barbara Cruise, who said the two had had conversations about the state of the Dawsons' marriage.
"My recollection is that there were some marital problems in the home, I think she felt that her husband had lost interest in her, is what I got out of the conversation, which concerned her, of course," Ms Cruise told the court.
"Her husband didn't appear to be, his interest appeared to be waning, let me put it that way."
She told the court that she received a phone call from Chris Dawson about January 11 in 1982 saying that Ms Dawson had "gone away and needed some time out" and that he "didn't know when she would be back".
Earlier in the day the witness known as JC, who married Mr Dawson after Ms Dawson vanished, concluded four days of evidence.
The trial continues.
