SYDNEY, May 23, 2025 (BSS/AFP) - Three Australians died of organ failure after eating a beef Wellington dish laced with toxic mushrooms, a medical specialist said Friday during a triple-murder trial sparked by the deaths.

Erin Patterson, 50, is charged with murdering the parents and aunt of her estranged husband in 2023 by serving them a hearty lunch laced with lethal death cap mushrooms.

She is also accused of attempting to murder her husband's uncle, who survived the meal after a long stay in hospital.

Patterson has pleaded not guilty to all charges in a trial that has drawn intense interest from around the world.

Intensive care specialist Stephen Warrillow told the high-profile trial on Friday how doctors had scrambled to save the lunch guests.

But as the toxins coursed through their bodies, causing multiple organs to shut down, there was little they could do.

"It was very apparent that this was not survivable," Warrillow said, talking about one of the victims he treated.

Another victim got "relentlessly worse" even after receiving a liver transplant, he said.

"We had no other treatments to offer, no other therapies. He was dying," the doctor said.

Warrillow was asked if the organ failure was caused by mushroom poisoning.

"That's correct, yes," he told the court.

Patterson was estranged from her husband Simon, who turned down the invitation to the July 2023 lunch.

But his parents, Don and Gail, died days after eating the beef-and-pastry dish.

Simon's aunt Heather Wilkinson also died, while her husband Ian fell seriously ill but later recovered.

- 'Sick of this' -
The court earlier heard how Erin Patterson had sent messages to a Facebook group chat in December 2022, several months prior to the lunch, saying she wanted "nothing to do" with her in-laws.

Patterson and estranged husband Simon were at odds over finances and child support, the court heard, and she had sought help from his parents, who refused to intervene.

"I'm sick of this shit I want nothing to do with them," Patterson wrote in one message.

The prosecution alleges Patterson deliberately poisoned her lunch guests and took care that she did not consume the deadly mushrooms herself.

Her defence says it was "a terrible accident" and that Patterson ate the same meal as the others but did not fall as sick.

The trial is expected to last another two weeks.