A Sydney woman mutilated her former lover's penis and flushed part of it down the toilet because she thought he was a "serial predator", a court has heard.
Jian Chen has pleaded guilty to the manslaughter of Xian Peng, 48, in February 2011.
According to facts previously presented to the court, police said she used sleeping pills to spike the soup she gave her former partner at her North Ryde home on February 9.
Once Mr Peng was asleep, Chen allegedly bound his hands and feet and stabbed him a number of times in the neck and groin before attempting to cut off his penis.
In a sentencing hearing on Friday, the NSW Supreme Court heard Chen, who at times cried in the dock, was suffering from "substantial impairment" at the time of the killing.
In his submissions, crown prosecutor Mark Tedeschi, QC, said Chen killed her former lover out of anger over the way he treated women.
Mr Tedeschi said Chen believed Mr Peng was a "serial predator in that he would make financially affluent women pregnant and use the fact that these women had a child with him to extort money from them".
Her anger was demonstrated through the "atrocious disfigurement that she caused to the deceased's genitals", Mr Tedeschi told the court.
The court heard Mr Peng was tied up for about six hours from midnight to about 6am on the night of the killing, and the attack took place during this time.
The court heard Chen cut off a piece of Mr Peng's penis before flushing it down the toilet.
"In essence, he was disfigured in his genital area while still alive," Mr Tedeschi said.
He argued the offence was at the "most serious end of this category of manslaughter", noting that it demonstrated "extreme violence".
Defence counsel Peter Hamill, SC, said Chen's anger and fear were the result of a depressive illness.
He said she "lost control" on the night of the attack and had a diminished capacity to reason at the time.
He also urged Justice Monika Schmidt to take into account Chen's lack of prior criminal convictions and her good prospects of rehabilitation.
Earlier, Chen's ex-husband, Michael Leung, said the attack was not in keeping with her character.
"Normally, she was a gentle, kind and polite person," he told the court.
Mr Leung said Chen had never acted violently towards him, and was a dedicated mother who had done her best to care for her children, even while in custody.
Justice Schmidt reserved her judgment.
