Lawyers for Erin Patterson argue that allowing jurors to stay in the same hotel as police and the prosecution while they deliberated over their verdicts in the triple murder trial represented a “catastrophic” failure of the justice system.

On Wednesday, three judges of Victoria’s highest court started hearing two appeals – by Patterson herself and the state’s director of public prosecutions (DPP) – into the conviction and sentence in the case.

Patterson, 51, is appealing against her convictions, while the DPP appealed against the sentence handed down to Patterson, arguing it is “manifestly inadequate”.

In September, Patterson was sentenced to life imprisonment, with a non-parole period of 33 years, for the murders of her estranged husband’s parents – Don and Gail Patterson and his aunt, Heather Wilkinson.

She was also convicted of the attempted murder of Heather’s husband, Ian Wilkinson, who survived the lunch after spending weeks in hospital.

Wilkinson was among a group of extended Wilkinson and Patterson family members in court for the hearing.

Patterson watched proceedings via videolink from Dame Phyllis Frost Centre, a women’s prison, and did not speak during the hearing.

Richard Edney, for Patterson, told the court of appeal on Wednesday that the failure to properly separate the jury during their deliberations – a process known as sequestering – was a fundamental irregularity that had denied her a fair trial.

The jury stayed in the same hotel as the police informant – the homicide squad detective in charge of the case – and lawyers from the office of public prosecutions while they deliberated on their verdicts.

Sequestering does not occur during every criminal trial, with Patterson’s lawyers arguing in their written submissions regarding the appeal that it was “an exceptional step to be taken only for an exceptional case”.

Edney said on Wednesday that it undermined the principle for justice “not only to be done, but to be seen to be done”, during one of the most high profile trials in Victorian history.

“What we say has occurred here in the applicant’s trial was an inexplicable and perhaps still unexplained failure of a process,” Edney said.

“We would describe the sequestration and what occurred during it as catastrophic.

“There has been a fundamental failure here to comply with the dictum I’ve been referring to.”

Edney said there was “an evidentiary vacuum” surrounding the sequestering, with no CCTV available from the hotel where the jury stayed, and the jury unable to be questioned on whether they interacted with anyone during their deliberations.

But he agreed there was no evidence any communication occurred, though argued that communication need not be verbal.

Justice Peter Kidd said there was no evidence that occurred either, nor that the jurors had regularly been separated from the official who ensures the integrity of their deliberations, the jury keeper.

“Even if you’re right that communication can be non-verbal, surely there must be something more than simply seeing somebody,” Kidd said.

“There can be a nod, a wink … there’s no evidence that’s occurred here.

“Maybe you won’t agree with me, but in this case it seems that the state of the evidence at all times was that there was no separation, and that the jurors were under the supervision of the jury keeper.”

Lawyers for Patterson also outlined the second, third and fifth grounds of her appeal on Wednesday, and started to expand on her sixth ground shortly before lunch.

Her second ground is that cell tower evidence and evidence of death cap mushroom sightings in Loch and Outtrim posted to a citizen science website should not have allowed in the trial as it was not relevant, or its value was outweighed by its unfair prejudice to Patterson.

The evidence on cell tower evidence, given by expert Dr Matthew Sorrell, was used by the prosecution to draw an inference that Patterson could have attended two locations reported on iNaturalist where death cap mushrooms had been sighted.

Patterson’s defence barrister, Veronika Drago, described the evidence as “dangerous” and “unfair”.

The third ground argues that trial judge Christopher Beale erred in ruling that photos and videos related to mushrooms and found on an SD card in Patterson’s home was inadmissible, as it tended to support her evidence that she foraged for mushrooms.

“Critical to the defence case was whether the applicant had previously foraged for mushrooms on occasions other than those alleged by the prosecution,” Patterson’s lawyers argue in their written submissions.

“That is, had the applicant innocently picked or foraged for mushrooms on other occasions or were the picking of death cap mushrooms, as alleged by the prosecution, isolated incidents?

“The first error by the trial judge – where the impugned evidence was incorrectly ruled to be irrelevant on 29 May 2025 – had a cascading and compounding effect on what came over the course of the following two days in the trial. It also occurred at a critical and sensitive time in trial.”

The fifth ground relates to “unfair and oppressive” cross-examination of Patterson, with her lawyers arguing in written submissions that it was “doused with impermissible conduct and was unnecessarily protracted”.

The cross-examination stretched over about six days.

The sixth ground is that prosecutor Nanette Rogers SC’s closing address caused a substantial miscarriage of justice.

According to written submissions, this occurred on 36 occasions where Rogers misstated the evidence.

Kidd told Edney it seemed as if a “calculated strategic decision” had been made by Patterson’s counsel at trial to allow the final address to maximise the possibility of acquittal.

“The complaints you are now raising, they were on the table at the time,” Kidd said.

At the start of the appeal hearing, Justice Stephen McLeish said that Patterson’s legal team were expected to make their arguments regarding her conviction appeal until later on Wednesday afternoon.

The prosecution will then respond to those submissions.

After submissions are heard regarding the conviction appeal, the court will turn to the DPP’s appeal against Patterson’s sentence. This argument relating to the sentence is not expected to be heard until Thursday afternoon.

The hearing continues.