Phone tower pings can’t tell precise location, expert tells Erin Patterson’s murder trial

A phone tower expert says he cannot eliminate the possibility Erin Patterson’s mobile phone was taken to spots near, but not in, the two Gippsland locations where prosecutors say death cap mushrooms had been found, and the discoveries posted online, by members of the public.

Dr Matthew Sorell told a Supreme Court jury sitting in Morwell he agreed the accused killer’s phone might have pinged nearby towers in Outtrim and Loch, but that connections to tower base stations could change with as little movement as a person going from the front door to the back door of their home.

Sorell said on Tuesday the records he examined showed Patterson’s phone might have been taken from Korumburra to Loch on April 28, 2023, and Leongatha to Outtrim on May 22, 2023.

The jury heard it was also possible there was a second visit to Loch on May 22, 2023, and that pings on towers from Leongatha to Outtrim suggested Patterson’s phone was in the area between 8am and 10am on July 29, 2023, the day of the fatal lunch.

Prosecutors allege Patterson visited areas where death cap mushrooms were sighted by a scientist and a mushroom enthusiast, who posted observations of the fungi in Outtrim and Loch on the publicly accessible iNaturalist website.

Erin Patterson is accused of murdering her parents-in-law, Don and Gail Patterson, and Gail’s sister, Heather Wilkinson, by serving them poisonous mushrooms in the beef Wellington lunch she cooked at her Leongatha home.

The Pattersons and Heather Wilkinson died in the days after the meal from the effects of mushroom poisoning. Heather’s husband, Ian, survived after weeks in hospital.

Erin Patterson has pleaded not guilty to three charges of murder and one of attempted murder.

Under cross-examination by defence counsel Colin Mandy, SC, Sorell said it was possible a phone inside a building could connect with separate towers depending on where a person holding it was standing.

“I can’t eliminate that,” Sorell said.

He said the results of his analysis were also limited by any Telstra outages during the 4½ years of Patterson’s phone data he was given to analyse, stretching from the start of 2019 to mid-2023.

Sorell agreed he wasn’t given the precise locations of the mushroom sightings or Erin Patterson’s home address, and was asked instead to look for possible visits to the postcode areas.

He said that in almost all the examples of possible visits, the data allowed for the possibility “of being in the area”.

Mandy said littered throughout call records shown to the jury were instances of a service moving between two base stations in quick succession.

“You could have a series of Leongatha [recordings], then a switch to Outtrim … then switch to Leongatha,” Mandy put to the expert.

Sorell agreed this was common, and did not mean the phone necessarily moved.

The trial continues.

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