Accused mushroom killer Erin Patterson is charged with the murder of three people and the attempted murder of another. Photo: AFP / PAUL TYQUIN
- The exact lethal dose of death cap mushrooms and potential survivability has been raised in the Erin Patterson murder trial.
- Erin Patterson is accused of using death cap mushrooms to intentionally poison four people at her home in 2023, an allegation she denies.
- A plant expert also told the court that residue in Patterson's dehydrator tested positive for death cap mushrooms.
Defence lawyers for accused killer Erin Patterson have suggested a person could survive death cap mushroom poisoning, even after eating the same meal as someone who fell seriously ill.
Patterson is accused of murdering three relatives by serving them a beef Wellington meal that contained poisonous death cap mushrooms.
Patterson has pleaded not guilty.
Victoria's chief toxicologist Dimitri Gerostamoulos returned to the witness box on Friday for his second day of testimony, being questioned by the defence's Colin Mandy SC.
Toxicologist Dimitri Gerostamoulos continued his testimony on Friday. Photo: ABC News: Kristian Silva
The defence questioned Dr Gerostamoulos about all the factors that led to illness from death cap mushrooms, reiterating to the court that medical knowledge was based on animal studies.
"There are lots of variables that needed to be considered for that lethal dose," Dr Gerostamoulos said, including the age and health of the subject.
He said a lethal dose was considered to be 0.1 mg per kg of body weight.
Mandy raised a study which showed some people who consumed death cap mushrooms reacted with different levels of severity, which is categorised into four grades.
He told the court that in the first grade, a person may not develop liver or kidney issues even though they ate the same meal as people who reacted more severely.
The prosecution then posed a hypothetical scenario about two adults consuming the same amount of a meal containing death cap mushrooms, and one of the adults dying.
Prosecutor Sarah Lenthall asked Dr Gerostamoulos what would happen to the other person who ate the meal.
Dr Gerostamoulos told the court they would likely fall seriously ill but could survive, citing a 2024 case of a Victorian man surviving death cap poisoning after a stint in the ICU.
Toxin test results shown to court
The court was again taken through tables of laboratory test results, showing the level of toxins present in samples from each of the lunch guests.
Samples taken from Don Patterson and Ian Wilkinson tested positive for toxins found in death cap mushrooms.
However, samples taken from Gail Patterson and Heather Wilkinson tested negative for those toxins.
The four lunch guests were all tested between 25 and 32 hours after the lunch.
Two samples were taken from Erin Patterson 51 hours after the lunch and neither tested positive for death cap mushroom toxins.
These were blood and serum samples, fluids the defence noted cleared traces of the toxin faster than urine.
Patterson's children were also tested and no toxins were found in either of their systems.
Test found toxins in beef Wellington leftovers
Also on Friday, Dr Gerostamoulos explained the process of extracting samples from leftover food, which he said is a sometimes difficult but routine task for toxicologists.
The tests sought to detect toxins present in death cap mushroom, known as alpha and beta amanitins.
On Thursday, he revealed to the court that beta amanitins were found in samples of mushroom paste and beef analysed about a month after the 29 July lunch.
The court heard that leftovers were collected from two different places in Erin Patterson's home, but were put into one bag.
Dr Gerostamoulos said it was not an ideal way to receive the samples.
Leftovers of beef, pastry and mushroom paste found in Erin Patterson's bin were tested extensively by several experts. Photo: ABC News / File photo
The court also heard from a plant scientist who had separately analysed leftovers from the lunch.
David Lovelock, who specialises in plant virology and bacteriology, told the court he used a technique known as DNA barcoding to test the beef Wellington lunch and residue from a food dehydrator.
Earlier in the trial, the court heard Erin Patterson both purchased and later dumped a black Sunbeam food dehydrator, from which samples were taken.
The tests were more than 99 percent positive for death cap mushroom residue in the dehydrator, but Dr Lovelock said he found no evidence in the leftover food provided.
The trial continues.
- ABC
