An Australian woman murdered her husband's parents and aunt by lacing their beef Wellington lunch with toxic mushrooms, a jury has found at the climax of a trial watched around the world.

Keen home cook Erin Patterson hosted an intimate meal in July 2023 that started with good-natured banter and earnest prayer but ended with three guests dead.

Throughout a trial lasting more than two months, Patterson maintained the beef-and-pastry dish was accidentally poisoned with death cap mushrooms, the world's most lethal fungus.

But a 12-person jury on Monday found the 50-year-old guilty of triple murder, a crime that carries a maximum of life imprisonment.

She was also found guilty of attempting to murder a fourth guest who survived.

"I think it's very important that we remember that we've had three people that have died," said Detective Inspector Dean Thomas after the verdict.

"I ask that we acknowledge those people and not forget them."

The trial has drawn podcasters, film crews, and true crime fans to the rural town of Morwell, a sedate hamlet in the state of Victoria better known for prize-winning roses.

Newspapers have followed every twist of what many now simply call the "mushroom murders”.

'Delicious'

Family members of the victims declined to speak after the verdict, asking for privacy in a statement issued through police.

A lone friend of Patterson appeared overcome with emotion as she left the courthouse through a jostling media pack.

"I'm saddened. But it is what it is," she told reporters.

On July 29, 2023, Patterson set the table for an intimate family meal at her tree-shaded country property.

Her lunch guests that afternoon were Don and Gail Patterson, the elderly parents of her long-estranged husband, Simon.

Places were also set for Simon's maternal aunt Heather Wilkinson and her husband, Ian, a well-known pastor at the local Baptist church.

Husband Simon was urged to come, but he declined because he felt "uncomfortable.”

In the background, Patterson's relationship with Simon was starting to turn sour.

The pair, still legally married, had been fighting over Simon's child support contributions.

Patterson forked out for expensive cuts of beef, which she slathered in duxelles of minced mushrooms and wrapped in pastry to make individual parcels of beef Wellington.

Guests said grace before tucking in and prayed once more after eating, with Heather later gushing about the "delicious and beautiful" meal.

Death cap mushrooms are easily mistaken for other edible varieties and reportedly possess a sweet taste that belies their potent toxicity.

'Not survivable'

The guests' blood was swiftly coursing with deadly amatoxin, a poison produced by the death cap mushrooms known to sprout under the oak trees of Victoria.

Don, Gail, and Heather died of organ failure within a week.

"It was very apparent that this was not survivable," intensive care specialist Stephen Warrillow told the trial.

Detectives soon found signs that Patterson had dished up the meal with murderous intent.

Patterson told her guests she had received a cancer diagnosis and needed advice on breaking the news to her children, prosecutors alleged.

But medical records showed Patterson received no such diagnosis.

The prosecution said this was a lie cooked up to lure the diners to her table.

She also lied about owning a food dehydrator, which police later found dumped in a rubbish tip.

Forensic tests found the appliance contained traces of the fatal fungi.

"I agree that I lied because I was afraid I would be held responsible," Patterson told the trial.

A computer seized from her house had browsed a website pinpointing death cap mushrooms spotted a short drive from her house a year before the lunch, police said.

'Super sleuth'

Death caps are the most lethal mushrooms on the planet, responsible for some 90 percent of all fatalities due to consuming toxic fungi.

Baptist preacher Ian Wilkinson was the only guest to survive, pulling through after weeks in the hospital.

He told the court how guests' meals were served on four grey plates, while Patterson ate from a smaller orange dish.

But he could not explain why Patterson wanted him dead.

Patterson was a devoted mother-of-two with an active interest in her tight-knit community, volunteering to edit the village newsletter and film church services.

She was also a well-known true crime buff, joining a Facebook group to chew over details from infamous Australian murders.

Friend Christine Hunt told the jury. Patterson had a reputation as "a bit of a super sleuth".

Patterson said the meal was accidentally contaminated with death cap mushrooms but maintained through her lawyers it was nothing more than a "terrible accident."

"She didn't do it deliberately. She didn't do it intentionally," defence lawyer Colin Mandy told the trial.

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

The trial heard from doctors, detectives, computer experts, and mushroom specialists as it picked apart the beef Wellington lunch in forensic detail.

Confronted with countless hours of intricate expert testimony, it took the jury a week to find Patterson guilty.

She will be sentenced at a later date.