A handout sketch from the Supreme Court of Victoria of Erin Patterson, an Australian woman accused of murdering three people with a toxic mushroom-laced beef Wellington
A handout sketch from the Supreme Court of Victoria of Erin Patterson, an Australian woman accused of murdering three people with a toxic mushroom-laced beef Wellington AFP

An Australian woman promised a "special meal" for her husband's family before dishing up a beef Wellington with death cap mushrooms that killed three of them, jurors heard Wednesday.

On the opening day of a trial that has drawn global attention, Erin Patterson, 50, faced a jury accused of three murders -- including her parents-in-law -- and one attempted murder.

She has pleaded not guilty to all counts, with her defence saying it was all "a terrible accident".

Patterson "deliberately poisoned" her guests, Crown Prosecutor Nanette Rogers told the jury.

The accused cooked "individual beef Wellingtons, mashed potatoes and green beans", with her guests eating from four large grey dinner plates, while she ate from a smaller, orange plate, Rogers said.

Patterson invited her guests to lunch in late July 2023 at her home in the sedate Victoria state farm village of Leongatha, telling them she had a health issue to relate, the prosecutor said.

Her estranged husband Simon Patterson declined, texting her the night before that he felt "uncomfortable" going.

In a return text minutes later, Patterson said she was "disappointed", as she wanted to prepare a "special meal and that she may not be able to have a lunch like this for some time", Rogers said.

But her husband's parents, Don and Gail Patterson, decided to go, along with his aunt Heather Wilkinson and her husband, local pastor Ian Wilkinson.

During the lunch, Patterson claimed to have cancer and wanted their advice about how to tell her two children, the prosecutor said.

Medical tests later found no evidence she had the disease, Rogers said.

Within hours of the lunch, the four guests developed diarrhoea and vomiting, and were raced to hospital.

All were diagnosed by treating doctors with poisoning by death cap mushrooms, Rogers told the court.

Within days, Don, Gail and Heather were dead.

Ian, the pastor, survived after nearly two months in hospital.

Patterson went to the hospital two days after the lunch and complained she, too, was unwell, the prosecution said.

She initially refused medical assistance and left the hospital, but relented and returned for treatment, the court heard.

Patterson said her children had eaten beef Wellington leftovers.

But she claimed to have scraped off the mushroom paste and pastry because they were "fussy", Rogers said.

When medical staff demanded to see her children, Patterson resisted, saying she did not want them to "be panicked and stressed".

"She did not appear to be concerned about children's health but rather about stressing them out," Rogers said.

The children eventually received medical attention but did not have any symptoms of poisoning.

Rogers said Patterson knew that neither she nor her children had consumed the deadly mushrooms.

Police located beef Wellington remnants at Patterson's home, which were found under forensic investigation to have traces of death cap mushrooms, Rogers added.

Patterson allegedly told doctors she used fresh mushrooms from a supermarket and also dried mushrooms from an Asian grocery -- but she did not remember which one.

A Department of Health investigation was unable to trace any shop selling death cap mushrooms.

Days after the lunch, Patterson discarded a food dehydrator, which was later found to contain traces of death cap mushrooms, the prosecutor said.

Patterson's lawyer Colin Mandy said the poisoning was a "tragedy and a terrible accident".

"She didn't do it deliberately. She didn't do it intentionally. The defence case is that she didn't intend to cause anyone any harm on that day," he said.

Mandy said his client "panicked" in the days following the lunch because she was "overwhelmed by the fact that these four people had become so ill because of the food that she'd served to them".

While Patterson initially "lied" to police about foraging for mushrooms, she later admitted she had done so, the defence lawyer said.

"She denies that she ever deliberately sought out death cap mushrooms," Mandy said.

Patterson is being tried in the Latrobe Valley Law Courts in Morwell, south of Melbourne.

The trial is expected to last about six weeks.

Latrobe Valley Magistrates' Court building in Morwell, where an Australian woman is accused of murdering three people with a toxic mushroom-laced beef Wellington
Latrobe Valley Magistrates' Court building in Morwell, where an Australian woman is accused of murdering three people with a toxic mushroom-laced beef Wellington AFP
Journalists outside a court building in Morwell, where an Australian woman is being tried for the alleged murder of three people with a toxic mushroom-laced beef Wellington
Journalists outside a court building in Morwell, where an Australian woman is being tried for the alleged murder of three people with a toxic mushroom-laced beef Wellington AFP