Chris Dawson's murder trial has been told that, in the year before his wife Lynette went missing, she came home and found the family's 16-year-old babysitter naked in the pool.
Susan Strath worked with Ms Dawson at the Warriewood Childcare Centre on Sydney's northern beaches at the time she went missing in January 1982, and gave evidence in court on Tuesday.
She gave evidence that, sometime before Christmas 1981, the teenager known as JC had moved into the Dawson home at Bayview — a development Ms Dawson was accepting of, but unhappy about.
Ms Strath said Ms Dawson told her that one day in that period, she arrived home from work to find the teenager in a state of undress.
"She told me that she got home from work and the babysitter was in the pool naked, and Chris was somewhere in the house.
"And I said 'I don't think the babysitter should be living there with you'."
She said Ms Dawson responded that JC had nowhere else to go.
"I said, 'I don't think that's your problem'."
The Crown alleges Chris Dawson murdered his wife on or about January 8, 1982 in order to have an "unfettered relationship" with the girl, who was also a student at the school where he taught.
Another witness and former colleague, Anna Grantham, told the court Ms Dawson disclosed an incident in which Mr Dawson assaulted her on the Bayview property beside the pool when the two were having a fight.
"She said he grabbed her by the back of her hair and he pressed her by the face, on the mud," Ms Grantham said.
"I said, 'Oh my god, he could have obviously killed you'.
"She said 'Yes, he could have easily killed me... I could not breathe, I was gasping for breath'."
Defence barrister Pauline David suggested Ms Grantham had created a false story in order to portray Mr Dawson as a "terrible man".
"You have listened to so many people say so many things about Mr Dawson that you wouldn't actually know what was said to you by Lynette Dawson," she said.
"Could you be confusing what Lynette Dawson said to you with something that somebody else has told you Lynette Dawson has said?"
"No, I don't think so," Ms Grantham responded.
On Monday, another former colleague, Annette Leary, testified she noticed bruising on Lynette Dawson's throat in the days before she disappeared, and that Ms Dawson confided to her that her husband had grabbed her around the throat in an elevator.
Ms Strath told the court that, on the Friday before Lynette Dawson's disappearance, Chris dropped her off at the childcare centre after a marriage counselling session.
She said they were holding hands at the time, and that Ms Dawson sounded "positive" in a conversation that followed.
"She said 'I'm hoping that we can move forward and work together.' She was very happy," Ms Strath said.
