Mushroom murderer Erin Patterson will likely die in prison after she lost a bid to overturn her convictions and her non-parole period was set aside.
On Friday morning, the court dismissed Patterson's appeal, finding she received a fair trial.
However the judges ruled in favour of a Director Public Prosecutions appeal that her 33-year non-parole period was inadequate for the premeditated poisonings.
Justice Stephen McLeish said Patterson intended to murder all four of her lunch guests for nearly three weeks prior to the incident and that the sentence should reflect that.
"It represented a cruel breach of trust to members of the applicant's extended family," he said.
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"On that basis, the appeal against sentence succeeds, and the non-parole period fixed by the judge will be set aside.
"In re-sentencing, it is necessary that the sentence vindicates unequivocally the primary value that our society places on each individual human life."
The non-parole period was set aside and Patterson will now spend the rest of her life behind bars.
The COA's ruling marks the latest chapter in a case that shocked the nation following a home-cooked family lunch in regional Victoria in July 2023.
Patterson was found guilty of murdering her former parents-in-law, Don and Gail Patterson, both 70, and Gail's sister, Heather Wilkinson, 66, after serving them beef Wllingtons laced with lethal death cap mushrooms at her Leongatha home.
Heather's husband, Church pastor Ian Wilkinson, spent nearly two months in hospital with critical organ damage before eventually recovering.
Following a nearly three-month trial, Supreme Court Justice Christopher Beale sentenced Patterson in September 2025 to life imprisonment with a 33-year non-parole period.
However, Patterson's appeal barristers argued that significant issues at trial invalidated her convictions.
Primarily, her defence said the jury was insufficiently sequestered during deliberations, as it emerged that jurors were accommodated in the same hotel as the Crown's primary police investigator and two prosecutors.
They also argued that the Crown's five-day cross-examination of Patterson was needlessly aggressive and that the prosecution incorrectly changed its case by suggesting a fresh motive during closing remarks.
At the same time, Chief Crown Prosecutor Brendan Kissane argued that the court should impose a harsher sentence and that Patterson be stripped of her right to parole.
The prosecution maintained that the killings involved calculated premeditation, exacerbated by her failure to tell medical staff about the death caps her victims had consumed while doctors were still trying to save them.
Patterson was not in the courtroom when the judgement was handed down, instead observing via video link from Dame Phyllis Frost Centre in Ravenhall, where she is serving a life sentence.
Active suppression orders remain strictly enforced for the media and the public.
Patterson's children and their schools cannot be named while rebroadcasting, photographing, or replicating any part of the court's live stream is a criminal offence.
