Killer uncle Xie abused me: Brenda Lin

The sole surviving member of the Lin family says her uncle, convicted killer Robert Xie, sexually abused her.

Brenda Lin was 15 and overseas on a school trip when Xie bludgeoned her parents, her two little brothers and her aunt to death in their Sydney home in July 2009.

In an interview on Seven Network's Sunday Night program, Ms Lin broke her silence on a motive behind the murder.

"Did your uncle Robert Xie sexually abuse you?" host Melissa Doyle asked her.

"Yes he did," Ms Lin replied.

"That's something I'm very private about and that at this point in time I don't feel comfortable talking about.

"So I hope people can respect that."

The murders left Ms Lin an orphan so she went to live with Xie and his wife Kathy Lin, the closest family she had.

She said she was unsure of herself at the time, and her uncle knew this.

"I was very insecure," she said. "I didn't know what I was doing. He knew that. He read it very well."

Ms Lin broke down in tears throughout the interview as she spoke candidly of the pain of losing her family.

"I'd give anything to have my family back," she said.

But she said her outlook on life had improved because after many good people reached out in support.

A jury found Xie used a hammer-like object to inflict horrific head injuries on his wife's family members as they slept. He was jailed for life.