The sister of a Sydney woman who decapitated their mother has told a court she will never forgive her.

Jessica Camilleri was found guilty of manslaughter in 2020 after she repeatedly stabbed her mother, Rita, in the kitchen of their St Clair home in 2019.

A trial heard the 27-year-old was in a fit of rage and was impaired by multiple mental disorders at the time.

Kristi Torrisi says her sister Jessica Camilleri was repeatedly offered help but always refused. Photo: ABC

On Wednesday, her sister, Kristy Torrisi, fought back tears as she told a court of the anxiety, pain, depression and anger she feels after her mother was taken by the “selfish hands” of her own sister.

“She was killed and butchered like she was nothing,” Ms Torrisi told a sentencing hearing at the NSW Supreme Court.

“I will never forgive, nor forget, a single thing about that evening.”

Ms Torrisi said Jessica was repeatedly offered help from the family and professionals, but it was her own choices in refusing that help that led her to court.

She described her mother as “a beautiful woman inside and out”.

“She had a heart of gold and always put others before herself, including Jessica,” Ms Torrisi said.

“Not a day goes by when I don’t think of my mother’s infectious smile, cheeky giggle, or wish her name would come up on my phone again.”

Rita Camilleri’s sister, Mary Hill, told the court Rita’s “unconditional love” for her daughter was “remarkable”.

She recalled talking to Rita many times, concerned Jessica was going to hurt her.

“She was blinded and couldn’t see what I could see,” Ms Hill said.

“She was a mother and a mother’s love knows no boundaries.”

Rita Camilleri always put others before herself, the court heard. Photo: Supplied

Ms Hill also said until there was more funding for mental health services, courts would see more “tragic cases”.

“Rita and Jess had been let down on many occasions by many services,” she said.

“I pray that Jess will get the help she needs, so Rita can rest in peace knowing her daughter is being looked after by a system that let her down.”

Rita Camilleri’s niece, Stephanie Cook, also said the family had been let down by a poor mental health system.

“I knew she was deeply disturbed for a long time,” Ms Cook said.

“Jessica scares me. I fear the day I lay my eyes on her again without [her] being behind bars.”

Camilleri’s barrister, Nathan Steel, said she had shown remorse, including in a letter to her family.

She wrote: “It didn’t hit me at first, but then it hit me like a tonne of bricks, like a mountain.

“I know it’s all my fault that my mother isn’t here.”

Mr Steel also pointed to Camilleri’s immediate confessions to police on the night of the killing and said she had given an “extraordinarily candid account”, adverse to her own interests.

The court has previously heard Camilleri initially blamed her mother for attacking first, but later abandoned that version of events and admitted she was the aggressor.

-ABC