An Australian appeals court on Friday ruled that triple murderer Erin Patterson must spend the rest of her life in prison, citing the "shocking criminality” of her poisoning four relatives of her estranged husband with deadly death cap mushrooms.

A three-judge panel of Victoria state’s Court of Appeal dismissed Patterson’s challenge to her convictions and upheld prosecutors’ appeal against the leniency of her original sentence. The ruling set aside her 33-year non-parole period, which would have made her eligible for parole consideration at age 82.

"The offending was extraordinarily cold and calculated and stands to be denounced in the strongest terms,” Justice Stephen McLeish said on behalf of the three judges.

"After anxious consideration, we have concluded that the case involved such shocking criminality that it is inappropriate to fix a nonparole period,” McLeish added.

Patterson is among the very few women in Australian history to receive a life sentence without the possibility of parole.

The first woman to receive such a sentence was Katherine Knight, a meatworker sentenced in New South Wales in 2001 for murdering her partner, John Price, the previous year. Knight stabbed Price at least 37 times.

Patterson’s convictions stemmed from a family lunch she hosted at her rural home in Leongatha in July 2023, where she served four relatives beef Wellington dishes laced with poisonous death cap mushrooms.

She was found guilty of murdering her former parents-in-law, Don and Gail Patterson, and Gail’s sister, Heather Wilkinson. Heather’s husband, Ian Wilkinson, survived after spending weeks in the hospital but was also the victim of an attempted murder for which Patterson was convicted.

Patterson was sentenced in September 2025 to three life terms for murder and 25 years in prison for the attempted murder of Ian Wilkinson. The sentences included a 33-year nonparole period.

She may still seek special leave to appeal to Australia’s High Court, the country’s highest judicial authority, although doing so would require meeting a high legal threshold.

Patterson has maintained her innocence and denied deliberately poisoning her relatives.

The deaths of Don and Gail Patterson and Heather Wilkinson within days of the lunch attracted widespread international media attention, turning the case into one of Australia’s most closely followed criminal trials.

The case has also inspired podcasts, books and screen adaptations.

Emmy-nominated actor Melanie Lynskey announced this week that she will portray Erin Patterson in a six-episode series for Paramount+, a subscription video-on-demand streaming service.

Lynskey will also serve as an executive producer on the series, which will dramatize the 97 days between the fatal lunch and Patterson’s arrest.

Prosecutors argued during an appeal hearing in August that Patterson should never become eligible for parole, saying her original sentence failed to reflect the calculated nature of the crimes.

McLeish said Patterson’s intention to murder all four lunch guests had been sustained for nearly three weeks, from the time she invited them to the meal through the preparation and serving of the poisoned food.

The judge also pointed to what he described as an "elaborate series of deceptions,” including Patterson’s false claims about having cancer, which she used to explain why her two children would not attend the lunch.

The only survivor, Ian Wilkinson, testified that Patterson had told her guests she wanted their advice on what to tell the children about her supposed diagnosis.

McLeish also noted that Patterson had destroyed evidence, denied foraging for mushrooms and repeatedly made false claims about where the mushrooms had come from.

"The offending was carefully planned and deliberate. It represented a cruel breach of trust,” McLeish said.

Patterson chose not to attend Friday’s hearing in person and watched the proceedings via video link from prison.

Because of her notoriety, she is held in the high-security Gordon Unit of Melbourne’s Dame Phyllis Frost Centre, a women’s prison where inmates considered at high risk from other prisoners are housed for their protection.

During her sentencing in September 2025, trial judge Christopher Beale said there was a "substantial chance” Patterson could remain in solitary confinement for years.

Patterson’s estranged husband, Simon Patterson, had also been invited to the lunch but declined the invitation the day before.

Evidence presented before the trial revealed that Simon Patterson had previously expressed suspicions that his estranged wife might have tried to kill him.

He testified during a pretrial hearing that he declined the lunch invitation because he feared for his safety.