Mushroom murderer trial undermined by 'catastrophic' hotel mix-up, appeal court told

Lawyers for Australian mushroom murderer Erin Patterson say her conviction was undermined by a "catastrophic" mix-up that led to the jury staying at the same hotel as prosecutors and a key witness.

Patterson is serving a life sentence after killing three of her relatives and trying to kill another by serving them a beef Wellington containing death cap mushrooms at her Victoria home in 2023.

Her lawyers also argued some evidence in the trial was too speculative, while evidence crucial to their own case was wrongfully excluded.

At the same hearing, Victoria's Director of Public Prosecutions is appealing against the sentence, arguing a 33-year parole period is "manifestly inadequate".

Patterson's victims include her in-laws Don and Gail Patterson, both 70, and Gail's sister Heather Wilkinson, 66.

Patterson, 51, did not attend the Court of Appeal in Melbourne in person, opting to watch via video link from prison.

Also not present was Patterson's estranged husband Simon Patterson, who was meant to attend the deadly lunch but cancelled at the last minute, in part due to his belief that his wife had been trying to poison him for years.

Heather Wilkinson's husband Ian, the only surviving guest of the lunch, was in court.