Erin Patterson trial: Victoria’s chief toxicologist tells jury death cap mushroom toxins found

Samples taken from a dehydrator were found to contain toxins “exclusively” linked to death cap mushrooms, jurors in Erin Patterson’s trial have been told.

Victoria’s chief toxicologist Dimitri Gerostamoulos was called to give evidence on Thursday about a series of tests conducted at the Victorian Institute of Forensic Medicine.

He told the court the Institute was provided with a series of items for testing by police on August 29, 2023 – a month after Ms Patterson hosted a fatal lunch at her Leongatha home.

The items were leftovers from the lunch, a fruit platter, a white jug containing a brown liquid, and vegetable matter or debris located in a dehydrator.

Prosecutor Sarah Lenthall told Dr Gerostamoulos the jury a day earlier had heard from mycologist Camille Truong, who examined the leftovers under a microscope and found no traces of death cap mushrooms.

Asked to explain how the Institute’s testing differed, he said “we don’t rely on visual detection of compounds”.

“We rely on sensitive instruments to be able to detect very low quantities that are not visible,” he said.

Dr Gerostamoulos said no testing was conducted on the fruit platter, and no amanitins – toxins found in death cap mushrooms – were detected in the brown liquid.

But he said samples of meat, pastry and mushroom paste from the lunch were tested.

In three of four mushroom paste samples no alpha-amanitin or beta-amanitin toxins were found, but in one sample they detected beta-amanitin.

Beta-amanitin toxins were also detected in one meat sample, he said.

In samples supplied of “vegetable matter” located in a dehydrator, Dr Gerostamoulos said both alpha-amanitin and beta-amanitin toxins were detected.

Questioned by Justice Christopher Beale if those toxins were “exclusively” found in death cap mushrooms, Dr Gerostamoulos responded: “Yes”.

Dr Gerostamoulos is expected to return to the witness box when the trial resumes on Friday morning.

Ms Patterson is facing trial after pleading not guilty to the murder of three of her husband’s relatives and the attempted murder of one more.

Simon Patterson’s parents, Don and Gail Patterson, and his aunt Heather Wilkinson died from death cap mushroom poisoning in the week after eating a beef wellington at Ms Patterson’s home on July 29, 2023.

Heather’s husband, Ian Wilkinson, recovered after spending a month and a half in hospital.

Prosecutors allege Ms Patterson deliberately spiked the lunch with “murderous intent”, while her defence argues the case is a “tragic accident”.

The trial continues.