Standing outside Newcastle court, Tabitha Acret said she was outraged and disgusted by a judge's decision to jail Tyrone Thompson for 22 years and six months, with a non-parole period of 15 years and six months, for the brutal murder.
Ms Acret, who ran sobbing from the Supreme Court and collapsed on Friday after the jail terms were handed down, urged prosecutors to immediately appeal the sentence.
She said while no sentence could bring her daughter Mackenzie Anderson back, "we are outraged by today's outcome".
"Whilst this might be thought of as a good outcome for the courts, we are disgusted that this sentence is what they think the value of my daughter's life was worth," Ms Acret said.
"Justice (Richard) Weinstein's sentence was an insult to women globally and I call for an urgent appeal of this sentence."
Ms Acret said Thompson was on parole when he murdered 21-year-old Mackenzie and "I place a great deal of blame for my daughter's death on the justice system".
She said judges often handed down sentences which were far too light when the nation was in the midst of an epidemic of gender-based violence, and there needed to be an investigation into the practice.
Justice Weinstein had earlier told how Ms Anderson's murder in March 2022 involved a frenzied attack of such ferocity that one of the two kitchen knives he used had snapped.
Thompson stabbed the mother-of-one 78 times over two minutes.
Ms Anderson's family had been shattered by her murder and left with feelings of helplessness, despair and anger, Justice Weinstein said.
Her death at such a young age was "every parent's nightmare".
But the judge said Thompson's significant mental health issues, the domestic violence he suffered as a child at the hands of his violent, schizophrenic, drug-addled father, his difficult schooling, exposure to drugs and sexual abuse by a teacher had diminished his moral culpability.
Justice Weinstein said because of Thompson's "special circumstances", he would reduce the standard minimum sentence of 20 years for murder in NSW to 15 years and six months.
The judge detailed some of Thompson's past mental health issues, including how he had delusions of being poisoned by microplastics which he believed were turning him into a woman and of being controlled by a government run by the Kardashians.
Justice Weinstein said he did find Thompson, who watched the sentencing via audiovisual link from prison instead of facing his victim's grieving family in court, intended to kill Ms Anderson when he first started stabbing her.
Thompson, 25, was diagnosed with a complex post traumatic stress disorder and severe personality disorder but not considered psychotic at the time.
He had been due to stand trial for murder before pleading guilty earlier in April.
In a letter of remorse to the judge, Thompson claimed the pair had struggled with a knife and when his hand was cut "something inside me lost control".
Ms Acret had earlier told the court her daughter must have suffered a "fear no human should ever know" on the night she was murdered and had been convinced Thompson would kill her after being paroled.
Thompson and Ms Anderson had been involved in an on-again, off-again relationship since late 2019 marred by domestic violence.
He was jailed in October 2021 for assaulting Ms Anderson, intimidating her and destroying her property but was released on parole on March 9, 2022.
Thompson, who ignored an apprehended domestic violence order banning him from contacting Ms Anderson, killed her 16 days later after breaking into her apartment in the Newcastle suburb of Mayfield.
NSW Premier Chris Minns said he couldn't begin to imagine the pain being felt by Mackenzie's family.
"They rightly deserve justice for the horrific murder of their daughter," he said in a statement.
"I have been advised that the Office of the Director of Public Prosecutions is considering the sentence in line with the Prosecution Guidelines."
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