Inside the forensic journey to unmask a deadly mushroom meal

With blue rubber gloves stretched over his hands, Senior Constable Adrian Martinez-Villalobos reached into a red-lidded rubbish bin to retrieve remnants of a toxic beef Wellington lunch police say Erin Patterson fed her in-laws.

He found the leftovers, eye fillet tenderloin steak coated in mushroom paste and encased in pastry, partially crushed inside a Woolworths paper bag and seeping into the outdoor bin.

Erin Patterson’s house and car in Leongatha, pictured in August 2023.Credit: Joe Armao

Martinez-Villalobos carefully put the remnants inside plastic forensic bags to prevent leakage.

The local policeman was able to recover the food thanks to a quick-thinking doctor, who asked him to retrieve it as he cared in hospital for two deteriorating patients, Erin’s in-laws, Don and Gail Patterson.

A Victorian Supreme Court trial has heard details of the movements of the pricey meat over the next two days as it traversed eastern Victoria and metropolitan Melbourne to the desks of mushroom experts ready to examine whether it caused the illness which eventually claimed the lives of the Pattersons, Gail’s sister Heather Wilkinson and made her husband Ian critically unwell.

Witnesses told a jury the delicacy – cooked using the RecipeTin Eats cookbook by chef Nagi Maehashi – travelled in blue zip lock bags in a police car from Erin Patterson’s home to the Leongatha hospital.

It was then driven 116 kilometres north-west from Leongatha in the back of an ambulance with Erin Patterson as she made her way to Monash Medical Centre to be examined.

An urgent taxi transported the leftovers further east to the Royal Botanic Gardens, but mycologist Camille Truong had already left for the day.

As if following the script of the Ann Brashares novel the Sisterhood of the Travelling Pants, but for food, a colleague then dropped the food at Truong’s suburban home.

There the scientist extracted mushrooms from the leftovers with tweezers for the first time.

Truong didn’t see any death cap mushrooms inside, so she put the lunch leftovers in her fridge at home before taking them back to work and testing again later the next day.

Despite using specialist tools, she told the jury she was unable to visually identify traces of death cap mushrooms using her microscope, finding only common field mushrooms.

As the meal made its way across Melbourne, the court heard staff at Monash and the Austin hospitals were working around the clock to try to save the lives of the Pattersons and the Wilkinsons.

The baked leftovers, now four days old, continued their forensic journey next into the hands of the Health Department and Agriculture Victoria.

But still, the jury heard, there was no positive identification of the toxic mushrooms that were by now suspected of sitting decomposing inside the puff pastry wrapped morsels.

Ian Wilkinson at court this week.Credit: Justin McManus

On August 2, 2023, the leftovers were examined by David Lovelock, a virologist at Agriculture Victoria, who painstakingly examined the samples from the blue plastic bags.

Photographs of the travelling lunch food displayed to the jury show the mushroom paste was by now distorted and mashed.

Using DNA extraction techniques, Lovelock said he too was also unable to identify any death cap toxins in the sample.

Lovelock told the jury he was, however, able to detect death caps in samples taken from a dehydrator that Erin Patterson had used to dry mushrooms.

Agriculture Victoria virologist David Lovelock (left).Credit: Justin McManus

He said they tested the samples against DNA from Amanita phalloides (the scientific name for death cap mushrooms), ghost mushrooms and yellow staining mushrooms.

“We were able to detect Amanita phalloides in two of the seven test tubes,” he said.

Despite receiving treatment for suspected death cap mushroom poisoning on August 4, 2023, Gail Patterson and Heather Wilkinson died. The following day, Don Patterson also succumbed, unable to be saved by a liver transplant.

It would be another few weeks before the dissected beef Wellington sample continued its journey by road, this time to the Victorian Institute of Forensic Medicine in Southbank.

Don Patterson, Gail Patterson, Heather Wilkinson and Ian Wilkinson.

At 11.30am on August 29, 2023 – a month after the fatal lunch – the court heard the zip-sealed bags arrived at the Kavanagh Street building that also houses the state’s morgue.

Here, marked with the words biological hazard, the bags were photographed and emptied, again, onto four 12-centimetre-wide trays, picked apart and placed into nine clear vials with white lids.

Head of forensic science and chief toxicologist Dimitri Gerostamoulos says his department dissected the meal into tiny samples – separated into pastry, meat and mushroom paste – and let them sit for three hours in a solvent used to draw out substances for detection.

This time, for the first time, the court heard the tests finally confirmed doctors’ suspicions – traces of death cap mushroom toxins inside the mushroom paste and beef samples.

Dimitri Gerostamoulos, head of forensic science at the Victorian Institute of Forensic Medicine in Southbank.Credit: Justin McManus.

“I can’t comment on the way they’ve been handled, only on the fact we received them in a large ziplock bag,” Gerostamoulos told defence lawyer Colin Mandy, KC.

This court heard this week that it takes three tablespoons of death cap mushrooms, or about 50 grams, to kill an average-sized adult.

Gerostamoulos agreed the following factors could affect how someone recovers from ingesting toxic mushrooms: the amount they consume, the concentration of toxins within the meal, and their general health, age and weight.

The jury heard the toxins in death caps – alpha amanitin, beta amanitin and gamma amanitin – cause cells to stop replicating, and affect kidney and liver function.

“They are quite toxic in terms of their potency. They can lead to someone experiencing symptoms of diarrhoea, vomiting and feeling quite unwell,” he said.

Gerostamoulos said the toxins, which are only found in small amounts in the mushrooms, can also cause tissue necrosis, organ failure, and eventually lead to the patient’s death if they are not treated appropriately in hospital.

Samples taken from Don Patterson and Ian Wilkinson, Gerostamoulos says, also later tested positive for a mushroom toxin, known as alpha and beta amanitin.

Samples taken from Gail Patterson and Heather Wilkinson returned undetectable results. Gerostamoulos said this meant the levels were not detectable in the women’s samples – but that didn’t eliminate the possibility the toxin might have been present.

Erin Patterson has pleaded not guilty to three charges of murder and one of attempted murder. Her lawyers have said the deaths were a terrible accident.

The trial continues.

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