What we've learnt in the Erin Patterson mushroom murder trial so far

The trial of Erin Patterson, accused of murdering three people with a beef Wellington laced with death cap mushrooms, has now completed its third week in court in Melbourne. Australia Correspondent Aziz Al Sa’afin explains what we've learned so far.

Patterson has pleaded not guilty to three counts of murder and one count of attempted murder in a case that has captivated the nation. Her legal team says she panicked after "unintentionally" serving the meal.

The first week of the trial focused on the events leading up to the fatal meal and the complex family dynamics at play. The jury heard that the lunch, hosted at Patterson’s home in Leongatha near Melbourne in July 2023, was intended as a kind of reconciliation gathering with her ex-husband’s family.

The court was told the lunch guests - Gail and Don Patterson, Gail’s sister Heather Wilkinson and her husband Ian Wilkinson - all became violently ill shortly after the meal. Only Ian survived.

Key Witness: Simon Patterson, Erin’s ex-husband, gave evidence about the breakdown in their marriage and his communications with family members after the lunch. He told the court that one of the victims had alleged Erin ate from a different plate. The defence has argued that all the plates were different in colour and size.

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In the second week, the court was given a deeper look into Patterson’s relationships with family and friends, as well as her online activity.

The jury heard a police interview with Patterson’s son, who spoke about the hostile dynamic between his parents. Family members of the victims also took the stand to describe their final interactions.

The court also heard from members of a true crime Facebook group Patterson was active in. Some members claimed she had shared images of a black food dehydrator with mushrooms inside, and had previously boasted about adding mushroom powder to her meals.

Key Witness: Ian Wilkinson, the sole survivor of the lunch, testified about what happened that day. He told the jury that Erin allegedly refused his wife Heather’s offer to help plate the food. He also claimed Erin ate from a different dish. During cross-examination, defence barrister Colin Mandy SC suggested that once the plates were placed on the table, guests were free to choose any seat, implying there was no deliberate assignment of specific plates. But Wilkinson maintained there were four identical plates and one that was different.

The focus of week three shifted to medical and scientific testimony as the court heard evidence from multiple experts.

Dr Laura Muldoon, one of the doctors who treated Patterson, told the jury that she appeared clinically well and showed no signs of liver poisoning when she was discharged after the lunch. This is notable, given the prosecution’s claim that she consumed the same meal as her guests but from a different plate.

Internationally respected mycologist Dr Thomas May testified that he had identified death cap mushrooms in Outtrim, near Korumburra, and posted about them on a citizen science website in the weeks before the lunch.

In a significant development, another mycologist — Dr Camille Truong — examined the remains of the beef Wellington and found no evidence of death cap mushrooms. Instead, she identified common field mushrooms typically sold in supermarkets. Truong also noted death caps are not commercially cultivated and would not normally be found in store-bought produce.

Jurors were shown images of the meal remnants: a flaky pastry enclosing a brown paste.

Patterson had previously claimed to have cancer but intensive care specialist Professor Andrew Bersten said the Victorian Cancer Registry had no record of her receiving a diagnosis and no medical documentation supported this claim. The prosecution says Patterson lied to her family about this at the lunch which the defence said it also accepted was a false claim.

Another key moment came when the jury was shown CCTV footage allegedly depicting Patterson driving into the Koonwarra Transfer Station on the morning of August 2, 2023 - the day after she was discharged from Monash Medical Centre. In the footage, a woman is seen opening her boot and carrying something into the tip.

The tip manager, Darren Canty, told the court he was contacted by police two days later and handed over the CCTV. He said he asked an employee to inspect the area shown in the footage, where they found a food dehydrator. Police were called, and a detective later retrieved the item.

Victoria’s chief toxicologist, Dr Dimitri Gerostamoulos, also gave evidence. He told the jury that as little as 50 grams of death cap mushrooms — about one mouthful — can be fatal, though the effects vary depending on a person’s age, immune system, and underlying health. He said not everyone who consumes them will necessarily die.

Gerostamoulos also confirmed that two of the lunch guests — Don and Gail Patterson — tested positive for deadly death cap toxins, along with Ian Wilkinson. However, Erin Patterson, her two children, and Heather Wilkinson all tested negative. The toxin was found in residue from the food dehydrator and leftover mushroom paste used in the meal.

Key witnesses: Mycologist colleagues Dr Camille Truong and Dr Thomas May. Also intensive care specialist Professor Andrew Bersten, who reviewed Patterson’s medical records and told the court her symptoms after the lunch appeared consistent with a diarrhoea illness rather than liver toxicity.

There is no dispute that the victims died from consuming death cap mushrooms. The central question is whether Erin Patterson knowingly included them in the meal.

The prosecution must prove four key elements beyond reasonable doubt:

Justice Christopher Beale informed the jury that one of the most significant issues in the trial will be determining whether there was an intent to kill or cause serious harm beyond reasonable doubt.

A motive has not been presented by the prosecution. Legally, one is not required to secure a conviction, which in Victoria must be unanimous by the Jury.

One juror has since been discharged after it emerged he had discussed the case with people outside court.

The trial is expected to run for another three weeks. Further evidence from forensic experts and police is anticipated as the prosecution continues to build its case.

Patterson remains on bail and has denied all allegations.