Puzzles and jumps: End game in Erin Patterson mushroom murder trial

Erin Patterson is innocent of triple murder and jurors should not force "puzzle pieces" of evidence together just to find her guilty, her barrister says.

Colin Mandy SC reminded the Victorian Supreme Court jury that prosecutors had to prove the mushroom cook's guilt as he finished his closing address on Thursday.

"The prosecution can't get over that high bar of beyond reasonable doubt," Mandy said in his last remarks in the marathon trial in regional Victoria.

"When you consider the actual evidence and consider it properly... your verdicts on these charges should be not guilty."

Prosecutors allege Patterson, 50, intentionally poisoned her former in-laws Don and Gail Patterson, Gail's sister Heather and Heather's husband Ian Wilkinson with meals laced with death cap mushrooms.

Don, Gail and Heather died after consuming the beef Wellington lunch on July 29, 2023, served by Patterson at her home in regional Victoria, while Ian survived.

Mandy told jurors Patterson did not have a motive to kill her lunch guests and prosecutors had been selective with evidence to try to fit their story.

He referred to the jigsaw-puzzle analogy used by crown prosecutor Nanette Rogers SC, who suggested the individual pieces of evidence could be put together to find Patterson guilty.

Mandy cautioned against that approach.

"You can't force puzzle pieces together — when puzzle pieces don't fit naturally, you know you have the wrong piece in the wrong spot," he said.

"But prosecutors can... force the evidence to fit their theory."

Mandy argued a more appropriate analogy was high jump, adding prosecutors needed to "jump over the high bar" of proving beyond reasonable doubt that Patterson was guilty.

"Erin doesn't have to jump any bar at all," he said.

The barrister urged jurors to find that standard had not been met, saying if they believed it was merely possible Patterson intentionally poisoned the beef Wellingtons to kill her guests they should find her not guilty.

If the jurors believed there was a reasonable possibility it was all an accident, Mandy said they would also have to find her not guilty.

Patterson needed to be judged on her intention at the time of the meal, not her actions and lies afterwards, he said.

The defence barrister referred to her false claims of having a cancerous lump on her elbow, as well as lies about having and discarding a dehydrator.

"She did those things because she panicked when confronted by the terrible realisation that her actions had caused the illnesses of the people that she loved," he said.

Mandy also criticised elements of the prosecution case.

He maintained Patterson was unwell after the lunch despite allegations she was faking an illness to try to divert blame.

The barrister pointed to her hospital blood test results which showed she had low potassium, elevated haemoglobin and elevated fibrinogen.

Intensive care specialist Andrew Bersten's evidence was those results were consistent with stress in the body relating to a diarrhoeal illness, the court heard.

Mandy rejected the prosecutor's suggestion Patterson had those levels because of psychological stress.

He also claimed prosecutors inaccurately portrayed phone-tower data from when Patterson discharged herself from Leongatha Hospital.

She left the emergency department shortly after 8am on July 31, two days after the lunch, and did not return to the hospital for more than an hour.

Prosecutors alleged her phone connected to the Outtrim base station in that time period, which was consistent with Patterson driving along the Bass Highway.

That indicated she did not go home after leaving the hospital, as she had claimed, the crown said.

Mandy urged the jury to reject that suggesting, saying the evidence showed Patterson's phone connected to the Outtrim base station for less than three minutes.

The jury was sent home after he finished his closing address.

They will return to court on Tuesday to hear Justice Christopher Beale's final directions before beginning deliberations.