Mushroom cook Erin Patterson’s phone was detected near death cap mushroom sites months before she served a deadly lunch, a jury has been told.

Patterson’s phone records were shown in the Victorian Supreme Court on Monday as she stands trial for the murders of her former in-laws Don and Gail Patterson, and Gail’s sister Heather Wilkinson.

It’s alleged Patterson deliberately served them a beef Wellington laced with death cap mushrooms at her home in regional Victoria on July 29, 2023.

Heather’s husband Ian also ate the lunch but survived, and Patterson has been charged with his attempted murder.

She has pleaded not guilty to all of the charges.

Dr Matthew Sorrell, a digital forensics expert, told the jury Patterson’s phone was in the vicinity of Outtrim, about 20 kilometres south-west of her Leongatha home, on May 22, 2023.

There was a post published on the iNaturalist science website on May 21 showing death cap mushrooms had been located on Neilson Street in Outtrim, the jury was previously told.

Sorrell said Patterson’s phone connected to a cell tower near Neilson Street between 11.24am and 11.41am on May 22, although it was likely she could have stayed as late as 11.49am.

Patterson’s phone also pinged to a tower in Loch, about 25 kilometres north of Outtrim, earlier on May 22, the jury was told.

Sorrell said the data supported the proposition that Patterson was in the vicinity of the Loch township and recreation reserve between 9.24am and 10.01am.

Patterson’s phone connected to the Loch tower on April 28 as well, although Sorrell told the jury the data did not strongly support the proposition she attended the reserve.

Christine McKenzie, who worked as a Victorian Poisons Information Centre specialist for 17 years, told the jury she found death cap mushrooms at the Loch reserve on April 18, 2023.

McKenzie said she was walking with her husband and grandson when she saw mushrooms growing under an oak tree and realised they were death caps.

She pulled them out of the ground to photograph and then removed all she could find, placing them into a dog poo bag.

“Because of my training, I was very well aware of the toxicity,” she said earlier on Monday.

“It’s a popular area for people to walk their dogs … and I was very keen to remove all the samples I could find.”

McKenzie said she posted four photos of the mushrooms onto iNaturalist that afternoon, along with the exact location of where they were found.

She told the jury she had made dozens of posts to the “citizen science” website, mostly of fungi, because she was fascinated by mushrooms.

McKenzie said she was confident the mushrooms located in Loch were death caps because of her years of experience identifying them at the poisons information centre.

“I feel much more confident about [identifying toxic mushrooms] but as far as the wider fungi kingdom, I’m often as much in the dark as anyone else,” she said in evidence.

McKenzie confirmed she did not return to the oval in the days or weeks after spotting the death caps, although there was a risk more could have grown back.

The trial before Justice Christopher Beale will continue on Tuesday.