By Kellie Lazzaro

Defence lawyers have told a court that a woman who pleaded guilty to defensive homicide was regularly abused by her boyfriend, and he convinced her to kill a man.

Bonnie Sawyer-Thompson was 19 years old when she struck Jack Nankervis 70 times with an axe and knife, while he was “out to it” at a unit in Morwell on June 20, 2014.

The Victorian Supreme Court, sitting at Morwell, was told Sawyer-Thompson had met Mr Nankervis for the first time the day she killed him.

The court heard she was in an abusive, sexual relationship with Phillip Mifsud, who she had met on the internet.

“Phil brought the weapon into my house and said that if I didn’t do it, he was going to kill my family. I was freaking out,” Sawyer-Thompson told the court.

During more than two hours in the witness box, Sawyer-Thompson detailed alleged regular abuse inflicted on her by Mr Mifsud during their six-month relationship.

She said he cut off her pony tail, smashed a bottle over her head, burnt her with cigarettes, made her sniff petrol and injected her with drugs without her consent.

Her mother, Kym Sawyer also gave evidence that Mr Mifsud had “pooed” on her daughter.

“Yes, he was laughing about it,” she said, in evidence to the court.

Ms Sawyer said her daughter had told her Mr Mifsud was involved in Mr Nankervis’s death.

She said her daughter told her, “Mum, he made me do it. He said if I didn’t do it, he’d come after youse with a bullet.”

Victim and accused alone in house at time of incident

But under cross-examination, prosecutor Campbell Thomson told Sawyer-Thompson, “I suggest that was a fantasy, and that you had no reasonable grounds to believe there was a threat.”

In his opening address last week, Mr Thomson said Sawyer-Thompson killed Mr Nankervis believing it was necessary to defend her family from serious injury and death, but she did not have reasonable grounds to have that belief.

In an interview with police, Sawyer-Thompson said someone had told her to kill Mr Nankervis, but the court was told it was unclear who that person was.

The victim and Sawyer-Thompson were alone in the house when she killed him.

During Sawyer-Thompson’s committal hearing, Mr Mifsud denied telling Sawyer-Thompson that he wanted Mr Nankervis dead.

Cocktail of drugs allegedly taken before death

Sawyer-Thompson told the court Mr Nankervis had come to her house on the morning she killed him, to burn some clothes to avoid being caught for a home invasion.

“Phil said Jack needed to stay here because it was a safe house,” she said.

The trio allegedly took a cocktail of drugs together including ice, cannabis and liquid gamma hydroxybutyrate, or GHB.

“We were all pretty out of it,” Sawyer-Thompson told the court.

“Phil kept asking [Jack] if his drink tasted funny. Jack said to Phil, I know what you’re trying to do.”

When asked what happened next, Sawyer-Thompson told the court, “Phil put Jack’s hand in the toaster and I had to go into the kitchen and shove money down his throat.”

“He told me that I needed to hit him with a mattock,” she said.

“He told me that I had to hit him, and then I had to say that he sexually abused or assaulted me. He told me pretty much what to say after it had happened.”

“I did lie and I’m really sorry.”

Mr Mifsud’s DNA was found on the mattock used to kill Mr Nankervis, but he was at a Morwell bush reserve, in the presence of police, when the murder took place, and he has never been charged in relation to the crime.

He returned to Sawyer-Thompson’s house after the murder, and reported the death to police later that night.

Apology letter not enough, Sawyer-Thompson says

The court was told Sawyer-Thompson had a dependent personality and an IQ of 70, just one point above a diagnosis for mild intellectual disability.

While in a protection unit in prison, she wrote a letter of apology to Mr Nankervis’s mother.

“After hearing the family members speak the other day, that letter of apology isn’t good enough,” Sawyer-Thompson said.

“If I could change what I did, I definitely would take it back,” she said, crying in court.

Sawyer-Thompson was originally charged with murder, but instead pleaded guilty to the lesser charge of defensive homicide

Just days after Mr Nankervis’s death, the Victorian Government announced it was abolishing the defensive homicide offence, saying it had been intended to help domestic violence victims, but was misused by killers to escape murder convictions.

Lawyers have disagreed on Sawyer-Thompson’s prospects for rehabilitation.

Justice Michael Croucher will deliver a sentence in December.

This post originally appeared on ABC News.