The key people, timeline and evidence in Erin Patterson's mushroom murder trial

By Judd Boaz, ABC News Australia

Erin Patterson has been charged with the murders of three people and the attempted murder of another, following a lunch held at her home in 2023.

Ms Patterson's parents-in-law, Donald and Gail Patterson, along with relatives Ian and Heather Wilkinson, became violently ill due to a meal consisting of beef Wellington that contained death cap mushrooms.

Donald and Gail Patterson and Heather Wilkinson died from their illnesses, while Ian Wilkinson survived.

Erin Patterson has maintained her innocence since her arrest in November 2023, with her defence making the case that the poisonings were a "tragedy and a terrible accident".

A six-week trial is currently underway at the Latrobe Valley Law Courts in Morwell, with global media descending on regional Victoria to cover the case.

Here's what we know so far.

The people

Erin Patterson

Erin Patterson is accused of killing three people and attempting to murder a fourth person at a lunch at her home on July 29, 2023.

She has maintained her innocence, stating that although she lied to police, she did not deliberately seek out death cap mushrooms and did not intend to harm or kill anyone.

She is a university graduate and a qualified air traffic controller. She met her husband Simon Patterson when they both worked at Monash City Council.

She remains married to Simon Patterson, with whom she shares two children.

Her estranged husband described Erin as "very intelligent" and "quite witty".

He says she was an atheist before meeting him, and has struggled with depression and self-esteem issues over the years.

The court has heard that Erin has been financially stable for many years, and was the benefactor of an inheritance from her grandmother in 2006.

In 2019, Erin began making connections with other people online via a Keli Lane true crime Facebook group.

Simon Patterson

Simon Patterson is the estranged husband of Erin Patterson, from whom he has been separated since 2015.

His parents, Donald and Gail, and aunt and uncle, Heather and Ian, attended a lunch hosted by his wife Erin on July 29, 2023.

Simon says his relationship with Erin was mainly characterised by her leaving him multiple times.

In his testimony, Simon Patterson told the court Erin had said the way they related to each other was "toxic".

Their relationship deteriorated in late 2022 over disagreements regarding child support payments.

Donald Patterson

Donald Patterson is the father of Simon Patterson, and father-in-law to Erin Patterson.

He and Gail Patterson married in 1973 and had four children together.

The couple settled in Korumburra in 1984 and lived there until their deaths in August 2023.

The court has heard that of all her guests at the lunch in question, Donald was the one that Erin Patterson was closest to, sharing a love of science, knowledge and books.

Donald was a high school teacher before retiring in the early 2000s.

Donald died at 11:30pm on August 5, from multiple organ failure secondary to altered liver function due to clinically diagnosed Amanita mushroom poisoning.

Gail Patterson

Gail Patterson is the mother of Simon Patterson, and mother-in-law to Erin Patterson.

She and Donald Patterson married in 1973 and had four children together.

The couple settled in Korumburra in 1984 and lived there until their deaths in August 2023.

The trial heard that Gail had suffered from encephalitis (inflammation of the brain) a few years prior to her death, and had been struggling with issues around her recovery.

Gail died at 5:55pm on August 4, with multiple organ failure, resulting from altered liver function due to clinically diagnosed amanita mushroom poisoning.

Ian Wilkinson

Ian Wilkinson was the husband of Heather Wilkinson, with whom he had four children.

He has served as the pastor at the Korumburra Baptist Church since 1999.

Ian is the only member of the lunch party aside from Erin to have survived, and received a liver transplant after falling ill.

He is expected to give evidence during the trial.

Heather Wilkinson

Heather Wilkinson was the younger sister of Gail Patterson, and was married to Ian Wilkinson with whom she had four children.

She helped out at a local school as a teacher's aide.

During the trial, Simon Patterson revealed that after guests began to fall ill, Heather had asked him about the crockery used at the lunch.

"We didn't have much conversation but [Heather] looked a bit puzzled and she said, 'I noticed Erin served herself her food on a coloured plate, which was different to the rest'," Mr Patterson told the court.

Heather was the first of the lunch guests to die, passing away at 2:50am on August 4 from from altered liver function and multiple organ failure, with a clinical diagnosis of Amanita mushroom poisoning.

The Facebook Friends

Three friends that Erin Patterson met online have been called as witnesses in the trial.

Christine Hunt, Daniela Barkley and Jenny Hay were all members of a Keli Lane true crime Facebook group along with Erin Patterson.

This group eventually crystallised into a five-person private group chat, where members would talk about their personal lives.

Ms Hunt told the jury that Erin had described her marriage to Simon as "controlling" and "coercive", and that she had major concerns about leaving the children with him due to his lifestyle.

Cooking and recipes from RecipeTin Eats were also a favourite discussion topic in the group.

Ms Barkley and Ms Hunt described Erin posting to the group chat about her new purchase of a dehydrator and her use of it to dry mushrooms for use in food.

They also detailed Erin asking the group about making a beef Wellington in the weeks before the lunch, and her difficulties in finding an appropriate cut of meat.

The evidence

The dehydrator

A Sunbeam food lab electronic dehydrator owned by Erin Patterson was a subject of the police investigation.

Police say they found a Sunbeam food dehydrator with Ms Patterson's fingerprints on it dumped at the Koonwarra tip soon after the lunch.

Defence lawyers for Ms Patterson say she admits she panicked and lied to authorities, claiming in her initial police interview she had never owned a dehydrator.

Facebook friends of Ms Patterson told the court that Erin had posted about purchasing and using a dehydrator to a private group chat in the months before the lunch, explaining that she had been using it to dehydrate mushrooms.

The messages

Text message communication between Erin Patterson and her estranged husband Simon Patterson, both via SMS and the messaging app Signal, has been tendered as evidence.

Mr Patterson was asked to read many of these messages aloud to the court, including an exchange where he declined an invitation to the July 29 lunch:

Simon: Sorry, I feel too uncomfortable about coming to the lunch with you, Mum, Dad, Heather and Ian tomorrow but I'm happy to talk about your health and implications of that at another time. If you'd like to discuss on the phone, just let me know.

Erin: That's really disappointing. I've spent many hours this week preparing lunch for tomorrow which has been exhausting in light of the issues I'm facing and spent a small fortune on beef eye fillet to make beef Wellingtons because I wanted it to be a special meal, as I may not be able to host a lunch like this again for some time. It's important to me that you're all there tomorrow and that I can have the conversations that I need to have. I hope you'll change your mind. Your parents and Heather and Ian are coming at 12.30. I hope to see you there.

Further messages on Signal regarding childcare arrangements, financial matters and logistics around live-streaming from the local church were a focus for much of the first few days of the trial.

The phones

The prosecution alleged in its opening argument that Erin Patterson was using two phones and two separate SIM cards in the weeks before and after the lunch on July 29.

Police conducted a search warrant at Ms Patterson's home on August 5, taking her mobile phone.

Around this time, the prosecution alleges Ms Patterson conducted factory resets on her phone repeatedly.

It is alleged a second phone was in use by Ms Patterson, and this phone has never been recovered by police.

The mushrooms

Both the prosecution and defence agree that medical testing of the poisoning victims showed it was death cap mushrooms that caused the deaths.

The death cap mushroom - or Amanita phalloides - is estimated to be responsible for nine out of every 10 mushroom poisoning deaths.

While just one mushroom can kill an adult, death caps are said to taste pleasant and look similar to edible mushrooms used in cooking.

The innocuous look, feel and taste of a death cap mushroom means it can be hard for someone who has eaten one to even know they've been poisoned.

In its opening argument, the prosecution said all four lunch guests tested positive for toxins found in death cap mushrooms, or had autopsy findings consistent with pathology typically seen from ingesting death cap mushrooms.

The website

In its opening arguments, the prosecution introduced the website iNaturalist.org to the jury.

It was described as a website dedicated to "recording observations and citizen science uploads of plants, animal and fungi".

The court heard of two posts made to the iNaturalist site, logging the sighting of death cap mushrooms in the Loch and Outtrim areas.

The prosecution argues that Erin Patterson travelled to both of these areas soon after the posts were made to the site.

The plates

The plates used by Erin Patterson to serve her guests at the July 29 lunch have become a focus of questioning from both the prosecution and defence.

The court has heard Heather Wilkinson mentioned shortly before her death that Ms Patterson ate from a different-coloured plate than the rest of her guests.

On cross-examination from the defence, Simon Wilkinson told the court that Erin did not own much crockery, which may have explained the discrepancy.

Timeline of alleged events

During the opening arguments, the prosecution charted the history of Erin and Simon Patterson's marriage, and her relationship with her four lunch guests.

This is the timeline of events in 2023 before and after the lunch, as set out by the prosecution:

February 12 - 15

Erin allegedly starts using two mobile phones, known as Phone A and Phone B, using a SIM card with the number 04XX XXX 783.

March 24

Erin is told she has tested negative for cervical cancer after a self-administered screening test.

April 18

A user on iNaturalist, a website for tracking plants and fungi, finds death cap mushrooms in the Loch area and posts about them online.

April 28

The prosecution says Erin's mobile phone data suggests she travels to Loch before returning to Korumburra.

Two and a half hours later, Erin allegedly purchases a Sunbeam food lab electronic dehydrator from a Leongatha store.

March to May

Erin allegedly starts posting about dehydrating mushrooms in a true crime Facebook group, detailing how she put powdered mushrooms into different foods.

May 21

An iNaturalist user posts a photo and location of death cap mushrooms in Outtrim.

May 22

The prosecution says Erin's mobile phone data suggests she travels to Loch and Outtrim.

June 28

Erin allegedly tells Donald and Gail that she has an appointment with St Vincent's Hospital on this date, and tells Gail the next day a biopsy was taken of a lump in her elbow.

July 11

Erin allegedly connects a new SIM card with the number 04XX XXX 835.

July 16

Erin attends a service at Korumburra Baptist Church and invites Don, Gail and Simon Patterson and Ian and Heather Wilkinson to lunch on July 29.

July 28

Simon messages Erin, saying he will not be attending the lunch due to feeling too "uncomfortable".

July 29

Erin Patterson serves a lunch of beef Wellington to four guests at her home in Leongatha.

July 30

Don and Gail ring Simon, complaining of serious illness. They travel via ambulance to Dandenong Hospital.

Simon picks up Heather and Ian, taking them to Korumburra Hospital, then Leongatha Hospital.

Erin allegedly tells one of her children she feels unwell, and spends the day running errands with her children before serving them a meal she says is leftovers from the lunch.

July 31

Doctors at Leongatha and Dandenong Hospital confer about the poisonings. Don, Gail, Heather and Ian are transferred to the Austin Hospital in Melbourne.

Erin drops her children to school, then texts Simon and asks him to take her to hospital, but he tells her to get there herself.

Erin presents to Leongatha Hospital around 8am, but allegedly declines a full examination and checks herself out. Erin returns to the hospital around 9:48am. She is transferred to Monash Medical Centre, and meets Simon and her children there.

Don and Gail arrive at Austin Hospital.

August 1

Heather and Ian arrive at Austin Hospital.

Despite escalating medical treatment, Donald, Gail and Heather continue to deteriorate.

Erin is assessed by a doctor at Monash, who says she appears clinically well and all her vital signs are within normal limits. She is discharged from hospital about 1pm.

The Department of Health interviews Erin about the lunch. She says she bought dried mushrooms from an Asian grocer in Melbourne's south-east.

August 2

Erin allegedly conducts a factory reset on Phone B, which she had been using before February 12.

She allegedly drives to Koonwarra Transfer Station and Landfill, and deposits items into an e-waste bin.

Monash Council begins visiting Asian-style grocery stores in Melbourne's south-east to find products matching Erin's description.

August 3

A Victoria Police investigation is launched into the July 29 lunch.

Erin allegedly moves her SIM card with the number 04XX XXX 835 into Phone B.

August 4

Heather dies at 2:50am.

Gail dies at 5:55pm.

Police travel to Koonwarra Transfer Station and find a black Sunbeam dehydrator in an e-waste bin.

August 5

Donald dies at 11:30pm.

A search warrant is executed at Erin's Leongatha house, where police seize Phone B with SIM card number 04XX XXX 835.

Erin is taken to Wonthaggi Police Station and interviewed.

August 6

Erin allegedly remotely conducts a factory reset of Phone B, which is still held by police.

Erin allegedly continues to use Phone A with number 04XX XXX 783. Police say they never recover this phone.

August 11

The Department of Health concludes its investigation, and is unable to find any store selling mushrooms matching Erin's description.

September 11

Ian Wilkinson is moved into a rehabilitation ward after a successful liver transplant.

November 2

Police arrest Erin and charge her with three counts of murder.

The locations

Important locations in the case

Five of the major locations in South Gippsland named in the trial so far.