A year after her blockbuster trial, Australia’s notorious mushroom murderer is facing court again, in a bid to overturn her conviction.

Erin Patterson was jailed for life last September for murdering three relatives and trying to kill another with a toxic mushroom meal she served at her home in Leongatha, Victoria, in 2023.

But the 51-year-old says she did not receive a fair trial, citing problems with evidence, the actions of the prosecution, and an unusual mishap with the jury while they deliberated on their verdicts.

At the same time that Erin Patterson’s case is heard, prosecutors will also be appealing her sentence. The judge said Patterson could apply for parole after 33 years, but the prosecution says that’s “manifestly inadequate” and the triple murderer should never be freed.

Patterson killed her in-laws Don and Gail Patterson, both 70, and Gail’s sister Heather Wilkinson, 66, after serving them individual portions of beef Wellington containing death cap mushrooms at her home in rural Victoria in 2023.

Heather’s husband, Ian Wilkinson, a local pastor, survived the lunch after weeks in hospital and still has ongoing health issues related to the poisoning.

Patterson’s estranged husband, Simon Patterson, was meant to attend the lunch but cancelled at the last minute, in part due to his belief that his wife had repeatedly tried to poison him over several years.

After the trial, it was revealed that he had become so violently ill after eating several of her meals in the past that he had been in a coma, a large part of his bowel had been surgically removed, and his family were told to say goodbye to him twice as he was not expected to survive his ailments.

Erin Patterson maintained throughout the trial that she never meant to kill her relatives – that it was all a terrible accident, and her lies and attempts to dispose of evidence in the aftermath of the lunch were because she was panicking she would be blamed for the deaths.

Patterson won’t be attending the appeal in person. She’s chosen to appear via video link from Dame Phyllis Frost Centre, the maximum security prison on the outskirts of Melbourne where she’s serving her sentence.

Last November, her legal team filed a three-page document outlining the arguments they plan to make in an effort to overturn her conviction.

There are seven grounds for this appeal, which will be heard by three judges.

Firstly, there are bits of evidence Patterson’s lawyers say the jurors should never have seen: for example, mobile phone tracking data that indicated she’d travelled to places where death cap mushrooms were recently spotted.

Her lawyers also argue that evidence from “Facebook friends” should not have been allowed. That included online messages in which she ranted about her in-laws as well as her estranged husband Simon Patterson, at one point calling him a “deadbeat”.

All that evidence, Patterson’s team says, was not relevant and prejudicial, causing a substantial miscarriage of justice.

But her lawyers also argue that other pieces of evidence would have helped Patterson in court. Photos and images relating to her hobby as a long-time mushroom forager – and supporting their argument that the deaths were a tragic accident – had been wrongly excluded, the defence says.

Then there are their issues with the prosecution. Patterson’s team say they were inconsistent about a motive, starting the trial by saying they wouldn’t argue a particular motive, but ending it by implying there was one.

They also criticise the five days Patterson was cross-examined by barrister Nannette Rogers. At times it felt tense witnessing the two sparring in the courtroom, with Rogers accusing her of repeatedly lying. Patterson argues it was “unfair and oppressive”.

But the most intriguing aspect of the appeal document submitted by Erin Patterson’s lawyers relates to the jury deliberations.

Because there was so much hype around the case, there were steps taken throughout the trial to ensure the jury wasn’t influenced by friends, family or the media. When they began deliberating, they had to stay in supervised accommodation, with little to no contact with the outside world, until they reached a decision.

But according to Patterson’s lawyers, a “fundamental irregularity” occurred which “fatally undermined” the integrity of the verdicts.

It turns out that room shortages caused by the media frenzy in the regional towns around the courthouse meant the jury wound up sharing a hotel with members of the prosecution, a key police witness, and journalists.

The jury had a whole hotel floor to themselves, and the judge at the time said there was no evidence they had any interaction with anyone linked to the case.

Patterson’s team didn’t raise any concerns during the trial, but in their appeal filing said: “[This] requires the quashing of the convictions and an order for a re-trial so that justice cannot only be done but be seen to be done.”

The Department of Public Prosecutions (DPP) is appealing over the length of Patterson’s sentence.

Justice Christopher Beale last year agreed that Patterson’s crimes were the worst of their kind, but said his decision to allow parole after 33 years was influenced by the “harsh prison conditions” she faced.

He noted that she’d already spent 15 months in solitary confinement at the time of her sentencing. In solitary confinement, prisoners cannot mix and meals are delivered via a small opening in the cell door.

For her own safety, he added, there was a “substantial chance” that she would be held in an isolation wing “for years to come” because of the notoriety of her case.

The outcome of the appeal will not be known immediately after these hearings as the decision could take months.

If the three judges in the Court of Appeal choose to overturn her convictions, there are two options: a retrial or acquittal.

If the prosecution’s appeal is successful, Erin Patterson could see her parole period being extended beyond 33 years. Or she may even be sentenced to life without parole.