A mushroom mystery gripping Australia began to unravel Monday, with an amateur cook saying she accidentally put lethal fungi in a beef Wellington dish now linked to three deaths.

Rumours are swirling around a close-knit community in rural Australia after a family mushroom lunch ended with three people dead and a local preacher fighting for his life. Police believe the dish was tainted with “death cap” mushrooms, which grow freely in the rolling foothills surrounding Leongatha - a small town about two hours’ drive southeast of Melbourne.

The meal was cooked by community newsletter editor Erin Patterson, who has been named as a suspect because she appeared to remain in good health despite her four guests falling violently ill.

The investigation has fuelled intense speculation as police try to separate clumsy cooking from an alleged act of malice.

Patterson stressed on Monday she had unwittingly brought the mushrooms from an Asian grocery store and that the poisonings were accidental.

“I am now devastated to think that these mushrooms may have contributed to the illness suffered by my loved ones,” she reportedly said in a statement provided to Australian media.

“I really want to repeat that I had absolutely no reason to hurt these people whom I loved.”

Patterson prepared the beef Wellington for her estranged parents-in-law Don and Gail Patterson on the afternoon of Saturday, July 29.

She was married to Don and Gail’s son Simon but the couple had been living separately for some time.

Local Baptist pastor Ian Wilkinson and his wife Heather rounded out the guest list. Later that night the two couples started experiencing food poisoning symptoms and, with their health rapidly deteriorating, they sought the help of doctors at local hospitals.

Heather and Gail died the following Friday, Don died the day after that, and 70-year-old Ian is still clinging to life in a critical but stable condition.

“We are hopeful and continue to pray for his recovery,” Ian’s family said in a statement over the weekend.

“We are deeply moved by the outpouring of kindness, prayers, and support from family, friends and the broader community.”

‘I’m devastated’

Forensic experts have been testing a food dehydrator that was found at a rubbish dump nearby to see whether it contains traces of the toxic death cap mushrooms.

According to Australian media, Patterson has admitted dumping the dehydrator - saying she panicked and was worried about losing custody of her two children.

She reportedly said she bought the mushrooms from a local grocery store in Melbourne and that she too had fallen ill after eating them alongside her guests.

Patterson has forcefully protested her innocence, tearfully telling reporters last week that “I didn’t do anything, I love them and I’m devastated they are gone”.

She has not been charged and police have provided no evidence of wrongdoing.

Death cap mushrooms sprout freely throughout wet, warm parts of Australia and are easily mistaken for edible varieties.

They reportedly taste sweeter than other types of mushrooms but possess potent toxins that slowly poison the liver and kidneys.