Data quizzed after cook's phone pinged near mushrooms

Mushroom cook Erin Patterson's legal team have grilled a phone data expert on the limitations of using cell data in connection with a person's movements.

Patterson, 50, is facing the fourth week of trial in regional Victoria, where she stands accused of three murders by allegedly deliberately poisoning a beef Wellington she served to her former in-laws.

Don and Gail Patterson, 70, and Heather Wilkinson, 66, all died in hospital days after eating the meal cooked by Patterson in July 2023.

The fourth lunch guest, Heather's husband Ian Wilkinson, survived the meal and Patterson has been charged with his attempted murder.

She has pleaded not guilty to all offences and claims the poisonings were a terrible accident.

Digital forensic expert Matthew Sorrell gave evidence for a second day at the court in Morwell, Victoria's southeast, today.

Yesterday, he told the jury his analysis of Patterson's phone records showed she was in the vicinity of the Gippsland towns of Outtrim and Loch on May 22, 2023.

A post had been published on the iNaturalist science website on May 21, revealing that death cap mushrooms had been located on Neilson St, Outtrim, the jury was told earlier yesterday.

Another post on April 18 stated the poisonous mushrooms had been spotted earlier that day at the Loch recreation reserve.

Under cross-examination by Patterson's barrister Colin Mandy SC today, Sorrell admitted there were limitations to his analysis.

He explained that he used two types of records to analyse Patterson's phone – call charge records and event-based monitoring data.

"That data allows for the possibility of a visit?" Mandy asked.

"It allows for the possibility of being in the area," Sorrell replied.

"But it does not necessarily indicate there was a visit to those locations?" Mandy continued.

"There's nothing to indicate there was a specific visit to an address," the expert said.

Mandy probed whether it was easier to exclude that a phone was in a particular area than to confirm it was there, and Sorrell agreed.

The defence barrister told the jury Patterson lived about 20 minutes' drive from Outtrim and half an hour from Loch.

Mandy asked Sorrell whether a phone could switch cell towers at different locations from inside Patterson's Leongatha home, for example if she picked up her phone and walked to her door.

"I accept that proposition," Sorrell said.

"Even if you've only moved 20 or 30 metres?" Mandy continued.

"Yes," Dr Sorrell said.

Mandy listed other limitations of the analysis including that a visit to Outtrim might not be recorded if no SMS, phone calls or data had been accessed on the phone, to which Sorrell agreed.

One of the homicide detectives tasked with investigating the allegedly murderous lunch was called as a witness this afternoon.

Detective Senior Constable Khuong Tran told the jury he obtained CCTV for the case, including from a BP petrol station in Caldermeade.

In video shown to the jury, about 3.19pm on July 30 – the day after the mushroom meal – Patterson is seen getting out of a red vehicle and walking into the service station towards the bathroom.

Patterson, wearing a grey top and white pants with a black crossbody shoulder bag and sandals, spends about nine seconds in the toilets and then takes an item from the fridge before paying and leaving.

She said she had experienced stomach pain and diarrhoea the day after the beef Wellington and took herself to hospital on July 31, the jury was told previously.

The trial before Justice Christopher Beale will continue tomorrow.