The subject came "completely out of the blue" while the two women were lying down and talking in a tent during a camping trip in the Illawara region, the NSW Supreme Court heard on Monday.

The friend gave evidence that about two years earlier she had told the woman that she had been sexually abused.

And the woman then revealed that "something similar" had happened to her.

The friend told the court: "We were just lying there. I suppose we were just talking and she asked me: 'How come I can remain so normal.' "

The court heard that the woman then went on to say: "You know what happened ... something similar I suppose you would say happened to me.

"I don't want to talk about it but it was similar."

The alleged conversation happened in April, May or June of 2009, the court heard.

Mr Xie is on trial for murdering his brother-in-law Min "Norman" Lin, Min's wife Yun, "Lilly", her sister Yun Bin "Irene" Lin and Lilly's two sons Terry and Henry in their North Epping home on July 18, 2009.

The woman, who cannot be identified, has previously given evidence that Mr Xie touched her sexually before the killings and sexually abused her afterwards.

The friend gave evidence that after the conversation in the tent, the woman tried to avoid the subject and would "walk off" or "brush it off".

"I did ask her once in a while," the friend said.

"She would say I'm busy or she would run off, she would avoid that in general or anything to do with that topic.

"I told her I would always be here if she ever wanted to ask me questions or if she wanted to talk about it, she could talk to me."

When the friend was questioned by police at her home after the killings, she mentioned the conversation the two had shared at the camp.

Mr Xie has pleaded not guilty to murder in relation to the killings.

The Crown has argued that his sexual interest in the young woman was one of his motives for the killings.

The hearing continues.