WARNING: This story contains graphic content that some readers may find upsetting.

A Sydney woman who decapitated her mother has been found guilty of manslaughter after arguing she was impaired by multiple mental disorders.

Jessica Camilleri, 27, told a psychiatrist her macabre act was inspired by violent horror movies with which she was obsessed.

The NSW Supreme Court heard she repeatedly stabbed her mother, Rita, in their St Clair home in July 2019 before carrying the 57-year-old’s head outside and then asking neighbours to call police.

But Camilleri pleaded not guilty to murder, arguing an impairment of the mind caused her to lose control of her actions – and that its severity warranted the charge being reduced to manslaughter.

It took the jury just over two days to find Camilleri guilty of manslaughter.

Camilleri did not react in the dock as she learned her fate.

During the trial, jurors were shown video from a body-worn camera of one of the first police officers called to the gruesome scene.

“Can I ask, is my mum dead?” Camilleri said, covered in blood.

“Don’t think I’m insane, but you can’t bring her back to life?”

Camilleri told police she was “in a fit of rage like I’ve never been before” after her mother dragged her by the hair into the kitchen and grabbed a knife first, forcing her to defend herself.

“I wanted to give her a taste of her own medicine, but not to kill her,” she said during an interview.

But she gave a conflicting account when later examined by psychiatrists, admitting she was the one who dragged her mother and reached for the weapons.

Behaviour left mother at ‘wits’ end’

Psychiatrist David Greenberg, who was called by the Crown, said Camilleri was prone to “rage attacks” and diagnosed her with an intellectual disability, autism spectrum disorder and intermittent explosive disorder.

But a psychiatrist called by the defence, Dr Richard Furst, disagreed that her outbursts were caused by intermittent explosive disorder and compared them instead to “kids having tantrums” as a result of the remaining disorders.

Dr Furst said Camilleri had a “warped perception” of her favourite movies, which included The Texas Chainsaw Massacre, and agreed she may have been acting out a violent fantasy while overwhelmed by anger.

The court heard Camilleri stopped taking psychiatric medication six months before the attack in favour of seeking natural alternatives.

Her sister, Kristy Torrisi, said she was “constantly” demanding attention from their mother, who became tired and exhausted from being a sole carer.

The jury was also told of Camilleri’s repeated prank calls – which included threats to behead strangers – which left her mother “at wits’ end”.

Dr Greenberg said as a result of being relentlessly bullied and taunted at school, Camilleri learned to target her aggression for revenge, almost exclusively on females.

“Her sole support, her only real companion, was her mother,” he said.

Justice Helen Wilson thanked the jury for sitting on the trial, saying it had been difficult.

“The subject matter you have been asked to consider has been extremely confronting,” she said.

The judge said the panel would have counselling services available should they need it, after hearing “distressing evidence that can stay with you for a long time after the trial”.

The judge also said during the juror selection process, an “awful lot of people” had said they simply could not sit through a trial such as Camilleri’s.

Camilleri will be sentenced in February.

-ABC