A former northern beaches student of convicted killer Chris Dawson has told a Sydney court she was "groomed" and treated like his property, when he began a sexual relationship with her.
The 74-year-old has pleaded not guilty to one count of carnal knowledge of a girl more than 10-years-old, and under 17 years of age.
The woman, known by the pseudonym AB, began giving evidence in the NSW District Court on Tuesday.
Crown prosecutor Emma Blizard said the sexual activity took place at Dawson's parents' home in the latter half of 1980, when AB was in the senior years.
"From that day ... sexual activity took place frequently and it continued into 1981, and it would occur in various locations including his office at school, his car and later, his home," Ms Blizzard said.
Dawson was mostly blank-faced as he sat in the dock wearing prison greens.
Last year, Dawson was sentenced to a maximum term of 24 years in prison for murdering his first wife, Lynette Simms, in 1982.
In the Supreme Court, Justice Ian Harrison imposed a non-parole period of 18 years, and said he recognised the "unavoidable prospect" Dawson would probably die in jail.
Appearing via video link, AB told the court that since grade 10, Dawson had "singled her out for special attention," and made an effort to ensure she was placed in his class the following year.
"One of his favourite stories was that he'd seen me in the playground and he thought to himself, 'I'd really like to get to know her, she's beautiful'," she said.
"It softened me. I felt special because he said that."
Ms Blizard said AB had confided in Dawson about her unstable home life, which deteriorated after her mother's abusive partner moved into the family unit.
Intimacy between the two allegedly escalated throughout the school year in 1980, culminating in their first physical contact at a school sports carnival, AB said.
AB repeatedly described Dawson's behaviour as "grooming".
"He put his hand on my knee in front of everybody ... that was the first time he paid me that kind of intimate, as I see it, intimate attention," she told the court.
"Was that your bare skin or over your clothing," Ms Blizard asked.
"Bare skin," AB replied.
She said Dawson taught her to drive, and he first kissed her in his car during a driving lesson.
Within weeks, Dawson then took AB to his parents' home, which was unoccupied at the time, and the two of them engaged in sexual activity in a bedroom, according to the Crown case.
Despite attempts by Dawson to make her comfortable, AB said, she had been afraid and shaking.
"Did you tell any friends?" Ms Blizzard said.
"No, I was told to keep it a secret," AB said.
AB said she and Dawson would "kiss and canoodle" during weekly fitness classes run by the accused and his twin brother, Paul Dawson, at a different northern beaches high school.
"In the time when one twin was running a class the other was out the back with whatever student was their property at the time," she said.
"If his brother was running the class, the accused and I would duck out the back and there would be kissing and cuddling and canoodling ... then we would come back ... and Paul would go out the back with [another student]."
She said while she was still 16-years-old, sexual activity regularly took place in Dawson's office during recess and lunch at school, and at the home where he lived with his then-wife Lynette.
"I never saw my friends. I was also seeing him every Friday night ... It got out of control, the amount of time I was spending with him," she said.
Defence lawyer Claire Wasley reminded the court Dawson "[did] not have to prove a thing".
Dawson has not denied he had a relationship with AB, but he has disputed the timing of when the alleged sexual activity occurred.
Ms Wasley said Judge Sarah Huggett was not required to assess Dawson against "contemporary moral standards", but rather those that existed in the 1980s.
She noted that the conviction of murder should have no bearing on the outcome of the carnal knowledge trial.
At least 10 former school students are expected to give evidence for the Crown over the two-week trial.
