A former student taught by Chris Dawson has said she moved into his home days after his wife’s disappearance and was treated as a sex slave, housekeeper and babysitter.

Giving evidence in Mr Dawson’s murder trial on Thursday the woman, known only as JC, said that in August 1982 she was unhappy living in the teacher’s Bayview, Sydney, home.

She told the court she was left looking after the Dawsons’ two young daughters as an 18 year old at the time, because Lynette Dawson had vanished in January that year.

“I was 18. I was taking care of two children, having to learn to cook, having to learn to clean, having to learn to be the substitute housekeeper, sex slave, stepmother, babysitter, slave,” JC told the NSW Supreme Court.

JC described a car trip with Mr Dawson, now 73, to a building south of the Sydney Harbour Bridge in late 1981. With JC still in her school uniform, the pair stopped at the building with a chain link fence and he went inside.

When Mr Dawson returned, JC said he had tried to hire a hitman to kill his wife but opted not to because innocent people would be hurt.

A plan over Christmas 1981 for the pair to start a new life in Queensland was aborted when JC felt sick on the drive there and wanted to return to Sydney as she missed her family.

Wanting out of the relationship at the time, JC told the court she took a trip up to South West Rocks with her family in early January 1982. On a phone call during this trip, Dawson told JC his wife had left him, the court heard.

“He said, ‘Lyn’s gone, she’s not coming back. Come back to Sydney and help me look after the children and be with me’.”

Returning to the Dawsons’ Bayview home, JC said no one else was there. She moved in and a few weeks later was allowed to pick some of Ms Dawson’s clothing to keep as her own.

She described the wardrobe in the Dawsons’ bedroom as bursting with clothes, and said Ms Dawson’s jewellery including two diamond rings had been left there.

When asked where his wife was, JC said Mr Dawson gave various explanations including that she had gone away with “religious people” and that she had been seen variously in Perth or the NSW Central Coast.

JC said she was sceptical of the explanations, describing them as a way to “fob her off” and shut her up. She said Mr Dawson never provided any concrete evidence behind his claims.

Dawson and JC married in 1984 but separated in 1990.

The judge-alone trial continues.