Woman accused of killing three at deadly lunch made sick lie to ensure her children didn’t attend, court hears

The Australian woman who has been accused of murdering three people with a dish including poisoned mushrooms made up a lie about her health, the courts heard.

Erin Patterson was charged with three counts of murder in relation to the deaths of her former in-laws, Don and Gail Patterson, and Gail's sister, Heather Wilkinson, who had attended Ms Patterson's home in in Leongatha, Australia, for lunch.

The 50-year-old served up a beef Wellington, mashed potato and green beans, with the Wellington containing death cap mushrooms, which are lethal to humans even in small amounts.

Don, Gail and Heather all died while Heather's husband, Ian Wilkinson, ended up in hospital in 'critical condition', though he survived, with Patterson also being charged with one count of attempted murder.

She has denied all the charges presented against her.

Erin Patterson is on trial for three murder and one attempted murder charges (9News)

The court has heard how she made up a lie regarding her health in order to allegedly make sure her two kids didn't attend the lunch.

According to Crown prosecutor Nanette Rogers, Patterson announced to the group that she had cancer and wanted advice on how to 'break it to their children'.

Rogers continues to say that the group told Pattenson that it was 'best to be honest with the children', and 'prayed as a group for the accused’s health and wisdom in relation to telling the children'.

"It is the prosecution case, the accused used the false claim of cancer to ensure and explain why the children would not be present at that lunch on July 29." Rogers added.

Patterson’s defence lawyer, Colin Mandy SC, agreed that it was not disputed by both defence and prosecutors that Patterson had lied about her cancer diagnosis.

Text messages revealed in court also showed that she had invited her ex-husband, Simon Patterson, to the lunch - but he declined because he felt 'uncomfortable'.

Don and Gail Patterson died after eating the meal (Family Handout)

He wrote: "Sorry I feel too uncomfortable about coming to lunch with you, mum, dad, Heather and Ian tomorrow but am 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."

Patterson then replied that she found his decision 'really disappointing' as she had spent a lot of time preparing the lunch, adding: "It's important to me that you're all there tomorrow and that I can have the conversations that I need to have."

Her defence team denied that she had intentionally poisoned her guests, but rather it was 'a tragedy and terrible accident', with Mandy saying that Patterson 'did not intend to cause any harm to anyone on that day'.

The trial continues.