Why mushroom killer Erin Patterson is returning to court this week

Erin Patterson, dubbed 'the mushroom killer' after a sensational case, will return to court this week in a bid to overturn her murder convictions for deliberately poisoning three relatives.

Patterson, 51, was last year jailed for life with a non-parole period of 33 years after she was found guilty of murdering her estranged husband's parents, Don and Gail Patterson, both 70, and Gail's sister, Heather Wilkinson, 66.

She killed them by lacing beef Wellington with lethal death cap mushrooms at a family lunch at her Leongatha home in Gippsland, Victoria, in July 2023.

Patterson was also found guilty of attempting to murder Heather's husband Ian Wilkinson, who became gravely ill but survived.

Patterson argued the deaths were a tragic accident, claiming the poisonous fungi were unintentionally included in the meal, and she later covered up her actions in a panic.

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The case garnered unprecedented public and media attention and was the subject of several books, television shows and podcasts.

Patterson will face a two-day hearing that starts on Wednesday at Victoria's Court of Appeal in Melbourne's CBD.

The hearing is an application for leave to appeal, which is a formal request to the court to hear the appeal.

The prosecution and defence will submit written and oral arguments, before a full panel of three judges will determine whether the case has merit for an appeal.

If Patterson is successful, the court could quash her convictions and order a retrial, or acquit her.

If the court rules against her, her convictions will stand, and she will serve out the remainder of her sentence.

In that instance, she could appeal to the High Court, which is Australia's highest court and can overturn decisions made in lower courts.

The Director of Public Prosecutions is also appealing the length of the sentence, arguing Patterson — who will be 82 years old when she is eligible for parole in 2056 — should be locked up for life.