Melbourne (AFP) - Australian prosecutors asked judges Thursday to stiffen mushroom murderer Erin Patterson’s prison sentence – saying she should never be set free.

The 51-year-old was found guilty last year of murdering her husband’s parents and an elderly aunt in 2023 by serving them a beef Wellington lunch laced with lethal death cap mushrooms.

Patterson was also convicted of the attempted murder of her husband’s uncle, a small-town local pastor who survived the beef-and-pastry dish after weeks in hospital.

At a two-day Melbourne court hearing that came to a close Thursday, Patterson sought to overturn her triple-murder conviction while prosecutors demanded she stay in jail for life.

Following her conviction, Patterson was sentenced to life imprisonment.

But the trial judge ruled she would be eligible for parole after 33 years, when she would be 83, taking into account that much of incarceration would be spent in isolation due to the notoriety of her case.

Prosecutors insisted, however, that the evidence did not substantiate the claim Patterson would be in isolation for “many years to come”.

Patterson’s crimes involved “betrayal” and represented “worst-case offending”, they told Court of Appeal judges at a hearing in Melbourne.

The 33-year non-parole period did not reflect the seriousness of her crimes, Director of Public Prosecutions Brendan Kissane told the judges.

“In our submission 33 years for this offending is manifestly inadequate,” he argued.

“Indeed, our submission is that for this offending the respondent should be sentenced to life without parole,” he said.

“We of course know it’s a harsh submission to make, but we submit it is demanded by the nature of the offending in this case.”

- Mushroom murders -

Patterson’s trial last year drew podcasters, film crews and true crime fans to a courthouse in the rural town of Morwell, a sedate hamlet in Victoria better known for its prize-winning roses.

Audiences from New York to New Delhi followed every twist of what many now simply call the “mushroom murders”.

The motive of the killings remains a mystery.

Patterson watched this week’s proceedings at Melbourne’s Supreme Court via a live video link from her maximum-security prison, the Dame Phyllis Frost Centre in Melbourne’s western suburbs.

She could be seen shaking her head and closing her eyes during Kissane’s presentation, national broadcaster ABC said.

On Wednesday, Patterson’s lawyers urged the judges to quash her conviction.

She had suffered a “substantial” miscarriage of justice, they said, alleging a litany of irregularities and the misuse of evidence during the trial.

The judges will announce their decision at a later date.

A 12-person jury found Patterson guilty in July last year of murdering her husband Simon’s parents, Don and Gail Patterson, as well as his aunt, Heather Wilkinson, at her home in the Victorian farming village of Leongatha.

She was also found guilty of attempting to murder Heather’s husband Ian, a pastor who fell gravely ill but eventually recovered.