Mushroom cook Erin Patterson has been arrested after her meal killed three people

Erin Patterson has been arrested following a fatal lunch that left people three dead.

Erin, 49, cooked a mushroom-based meal in July, with her in-laws Heather Wilkinson, 66, Gail Patterson and Don Patterson, both 70, going on to pass away shortly after.

Meanwhile, Gail's husband Ian, 68, ended up in a 'critical condition' and was hospitalized at the time.

He spent two months in hospital and is the sole survivor of the ordeal.

The Pattersons were the parents of Erin's estranged husband Simon, whom she shares two kids with.

It's reported that Simon had also been invited to the lunch, but wasn't able to make it.

The Wilkinsons and Pattersons attended Erin's Leongatha, Victoria, home for lunch on 29 July, and were later suspected to have ingested death cap mushrooms.

Forensic tests went on to confirm that the mushrooms were their cause of death.

Erin then went on to be accused by her estranged husband Simon of poisoning his family, but she's always maintained her innocence.

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Now, over three months on from the incident, Erin has been arrested by police today (2 November) in the wake of their ongoing investigation.

The charges she's facing are yet to be revealed.

Detective Inspector Dean Thomas said in a statement: "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.

"Once the search of the premises is completed, the female will be interviewed by homicide squad investigators. We will provide updates through the day."

Noting the worldwide public interest the case has had, the detective went on to say: "Keep in mind that at the heart of this, three people have lost their lives.

"These are three people who by all accounts were much beloved in their communities, and they are greatly missed by their loved ones."

The arrest comes after police painstakingly executed a warrant at Erin's address using technology detector dogs.

The dogs are are trained to smell the chemical triphenylphosphine oxide (TPPO).

ABC

In previous interviews following the fatal lunch, Erin spoke of her love for her in-laws.

"I am now devastated to think that these mushrooms may have contributed to the illness suffered by my loved ones," she said at the time.

"I really want to repeat that I had absolutely no reason to hurt these people whom I loved."

The 49-year-old is now being questioned at Wonthaggi Police Station.