The mushroom poisoning trial captivated Australia. Why Erin Patterson did it remains a mystery

MELBOURNE, Australia — The high-profile case of the so-called Death Cap Mushroom Cook is likely to remain a topic of conversation across Australia for years to come.

For more than two months, the triple-murder trial has gripped the public's attention with details of how Erin Patterson murdered three of her estranged husband's relatives by deliberately serving them a lunch of poisonous mushrooms.

It was no surprise that on Tuesday — the day after the guilty verdict was delivered by the court in Victoria — media websites, social media and podcasts were scrambling to offer analysis on what motivated her.

Newspaper headlines described Patterson, 50, as a coercive killer with narcissistic characteristics. ''Cold, mean and vicious,'' read one.

Strict Australian court reporting laws prohibit anything that might sway jurors in a trial. Some news outlets had saved up thousands of words awaiting the verdicts: scrutiny of Patterson's past work history, behavior and psyche.

The coverage tried to explain why the mother of two meticulously planned the fatal lunch and lured three people she said she loved to their deaths. Any certain answer, for now, remains a mystery.

No motive

After a nine-week Supreme Court trial in the state of Victoria, it took the jury six days to convict Patterson. She was found guilty of murdering her parents-in-law, Don and Gail Patterson, and Gail's sister, Heather Wilkinson, by serving them a lunch of beef Wellington pastries laced with poisonous mushrooms.

She was also convicted of attempting to murder Heather's husband, Ian Wilkinson, who survived the meal at Patterson's home in the rural town of Leongatha in 2023.

Patterson denied poisoning them deliberately and contended that she had no reason to murder her beloved, elderly in-laws. But the jury rejected her defense that the inclusion of toxic mushrooms in the meal was a terrible accident.

Prosecutors failed to offer a motive for Patterson's crimes and weren't required to do so.

''People do different things for different reasons. Sometimes the reason is obvious enough to others,'' prosecutor Nanette Rogers told the jury. ''At other times, the internal motivations are only known by the person themselves.''

But Rogers gave hints. At one point, the prosecutor had Patterson read aloud scathing messages she'd sent which highlighted past friction with her in-laws and tension with her estranged husband, who had been invited to the lunch but didn't go.

''You had two faces,'' Rogers said. Patterson denied it.

'She had a dilemma'

With guilty verdicts but no proven reason why, Australian news outlets published avid speculation Tuesday.

''What on earth was Erin Patterson's motive?'' The Australian newspaper's editorial director Claire Harvey asked in a column. Harvey pointed at rifts in the killer's relationship with her estranged husband.

Chris Webster was the first medical doctor to speak to Patterson after her four lunch guests had been hospitalized and testified in the trial. He told reporters Tuesday that he became convinced she deliberately poisoned her victims when she lied about buying the foraged mushrooms she had served from a major supermarket chain.

''She had a dilemma and the solution that she chose is sociopathic,'' Webster told Nine Network television.

Displayed no emotion

The outpouring of scorn for Patterson reflects a national obsession with the case and a widespread view that she wasn't a sympathetic figure.

It was an opinion Australians were legally required not to express in the media or online before the trial ended to ensure a fair hearing. But newspapers now don't have to hold back.

Under the headline ''Death Cap Stare,'' The Age reported how the ''killer cook'' didn't flinch as she learned her fate, but stared at the jury as they delivered their verdict.

Melbourne's Herald Sun newspaper's front page screamed: ''COOKED,'' labelling Patterson ''Evil Erin'' and a ''Cold-Blooded Killer.''

During the trial, Patterson chose to testify in her own defense, a tactic considered risky in the Australian justice system and one which most observers said didn't serve her well. She joked awkwardly at times and became combative with the prosecutor.

Journalist John Ferguson, who won a Melbourne Press Club award for breaking the story of the fatal lunch, said Patterson often cried or came close to tears during her trial. But when she was convicted, she displayed no emotion, he noted.

''What the court got on Monday was the full Erin. Cold, mean and vicious,'' Ferguson wrote in The Australian Tuesday.

Drama series, documentary and books

The verdicts also prompted an online frenzy among Australians, many of whom turned citizen detectives during the trial.

By late Monday, posts about the verdicts on local Reddit pages had drawn thousands of comments laced with black humor, including memes, in-jokes and photographs taken at local supermarkets where pre-packaged beef Wellington meals were discounted.

Fascination about the case will linger. A drama series, documentary and books are planned, all of them likely to attempt an answer to the question of what motivated Patterson.

She faces life in prison, with sentencing to come at a later date. From then, Patterson's lawyers will have 28 days to appeal.

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Graham-McLay reported from Wellington, New Zealand.