Woman charged with murder following mushroom poisoning deaths.

The mushroom poisoning case is evolving as we speak. 

In July, at a standard luncheon among family in Victoria's South Gippsland shire, a meal that police have deemed suspicious was served. Four of the lunch's attendees died and one miraculously recovered.

Now a woman who was present at the lunch, identified as Erin Patterson, has been charged with three counts of murder and five counts of attempted murder. Court documents reportedly show that she is accused of attempting to murder her former partner, Simon Patterson, four times over the past two years.

"The murder charges and two attempted murder charges relate to an incident on 29 July where four people were taken to hospital after they fell ill following a meal at a private residence in Leongatha," a statement from police reads.

"The further three attempted murder charges relate to three separate incidents in Victoria between 2021-2022. It's alleged a 48-year-old Korumburra man became ill following meals on these dates."

Watch: the news of the arrest unfolds. Post continues below.

The 49-year-old was arrested by homicide squad detectives at her home in Leongatha just after 8am on Thursday. A search warrant was executed at the address with assistance from Australian Federal Police detector dogs.

"Today's arrest is just the next step in what has been a complex and thorough investigation by homicide squad detectives and one that is not yet over," he said.

"While police are doing everything we can to ensure this investigation is not impacted by this, again, I stress, at the heart of these matters, are the recent deaths of three people and families and loved ones who are trying to come to terms with this."

Gail Patterson and her husband Don, both 70, went to lunch at their former daughter-in-law Erin Patterson's home in Leongatha, around a two-hour drive from Melbourne.

Gail's sister, 66-year-old Heather Wilkinson and her 68-year-old husband, Baptist Church pastor, Ian Wilkinson, were also at the lunch. Erin Patterson had recently separated from Gail and Don's son Simon Patterson, police saying the pair described their separation as "amicable".

Simon Patterson was not present for that meal. It's been reported that he was supposed to be at the lunch. 

Mushrooms were used in a beef wellington which was served at the lunch. Police say it was Erin, 49, who cooked the meal at her home and served it.

Hours after ingesting the lunch, four of the family members became seriously ill, believing they had severe gastro. Police now believe their symptoms were related to ingesting death cap mushrooms.

Gail, Heather, Don and Ian all subsequently presented at the hospital. Police say Erin Patterson did not become ill. 

On August 4, the two sisters died in hospital. Don passed away in hospital the following night. Ian miraculously survived, after spending two months in hospital in a critical but stable condition. Upon his release, the Wilkinson family issued a statement, saying: "This milestone marks a moment of immense relief and gratitude for Ian and the entire Wilkinson family."

The investigation has involved homicide squad detectives, the Department of Health and other experts assisting. 

The woman identified as Erin Patterson has previously said to reporters: "I didn't do anything. I loved them and I'm devastated they are gone. What happened is devastating and I'm grieving too."

On August 11, she reportedly sent Victoria Police a written statement, which was obtained by the ABC. The publication reports that in the letter, she says she purchased the mushrooms at a supermarket and an Asian grocery store.

"I am now devastated to think that these mushrooms may have contributed to the illness suffered by my loved ones. I really want to repeat that I had absolutely no reason to hurt these people whom I loved."

The woman said she also ate the meal, which contained a mixture of button mushrooms purchased at a major supermarket chain, and dried mushrooms bought at an Asian grocery store in Melbourne months previously. 

Her children, who she said were not at the lunch, ate the leftovers the following night but they do not like mushrooms so she scraped them off the meal, ABC and The Guardian reported. She also said she was hospitalised and was put on a saline drip and a "liver protective drug". 

After the onset of symptoms, she said she was contacted by the Department of Health and provided what was left of the lunch to toxicologists for examination. She also said she told investigators where she bought the mushrooms, but she was unable to identify the specific shop in Melbourne where she obtained the dried fungi.

South Gippsland mayor Nathan Hersey has said the small Korumburra community has been in mourning since the deaths of Gail, Heather and Don.

"It's hard because we've had a lot of people experience a lot of grief all at once," Cr Hersey told AAP. "It's shock and it's grief and it's sadness and it's not just with one person that they love, but with three who they loved dearly who (have) passed away."

Feature Image: Getty.