Triple murderer Erin Patterson would have been unfairly prejudiced if a jury heard allegations she tried to kill her ex-husband in the years before a deadly mushroom lunch.

Victorian Supreme Court Justice Christopher Beale made the decision on March 14, ruling Patterson would have to face a separate trial for the three attempted murder offences.

Prosecutors ultimately dropped the charges in relation to Simon Patterson just before the triple-murder trial started in Morwell.

On July 7, Patterson was found guilty of killing Simon’s parents, Don and Gail, 70, and his aunt Heather Wilkinson, 66, along with the attempted murder of her husband Ian Wilkinson.

Beale’s redacted pre-trial rulings were released to media on Monday night, after Patterson lost her bid to keep the evidence a secret to preserve her appeal rights.

The details around the alleged attempted murders of Simon Patterson were revealed for the first time on Friday.

Prosecutors had alleged Patterson tried to poison Simon several times between 2021 and 2022.

The first was a penne pasta Patterson cooked him before leaving for a camping trip in November 2021, which led to a five-day hospital stay for Simon.

He also ended up in a coma after a camping trip in late May 2022 where he allegedly ate a chicken korma curry Patterson had made him.

Simon had to have surgery to remove a large portion of his bowel after eating the curry, he told the Supreme Court during pre-trial hearings.

It was also alleged he fell ill in September 2022 after eating a wrap Patterson prepared for him while camping together at Wilsons Promontory.

The prosecution claimed the allegations could be used as coincidence evidence to show the similarities between what allegedly happened to Simon and the mushroom lunch guests.

But Beale ruled the charges should be heard in a separate trial to prevent jurors from “misusing or overvaluing” the evidence in relation to Simon.

He determined if a jury found Patterson had deliberately poisoned her four lunch guests in July 2023, there was a risk they would wrongly assess the charges relating to Simon.

“I am not persuaded that its probative value substantially outweighs the significant danger or risk of unfair prejudice to the accused,” Beale said in his written reasons.

He also made pre-trial rulings in relation to documents about poisoning found on devices police seized from Patterson’s home.

Beale ruled the documents failed the relevance test because the evidence could only go as high as Patterson possibly accessed the file.

He also stopped the jury from seeing a Facebook post Patterson made to a poisons page, where she claimed her cat had chewed on a mushroom and was vomiting.

Beale noted the post was made 18 months before the first allegation in relation to Simon.

“In my view, even if the evidence of this post shows an interest in poisons, it is temporally remote,” he said in his reasons.

Patterson will face a two-day pre-sentence hearing later in August, during which she will listen to statements from the Pattersons and Wilkinsons.

She will have 28 days to appeal after she is sentenced.

-AAP