Erin Patterson is accused of killing three people with poisonous death cap mushrooms.
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Digital forensic expert returns to the stand
Digital forensic expert Dr Matthew Sorell has returned to the stand.
Patterson’s phone record over 18-month period examined by digital expert
The court has heard that digital forensic expert Dr Matthew Sorell examined Patterson’s phone records for an 18-month period from
During that period, he identified 57 data connections or mobile network events associated with the Loch area (including its surrounds).
The court has heard eight of those connections were identified as possible visits, while the remaining 49 were consistent with Patterson bypassing the Loch area.
Digital analysis finds ‘possible visit to Outtrim’ in days after the lunch, court hears
Sorell was also asked to examine Patterson’s phone records on July 31.
The court heard data connection events that morning were recorded as below:
8.31am - A connection to Leongatha base station
8.55am - A connection to Outtrim base station
9.23am - A connection to Leongatha base station
Asked by the prosecution what these phone records suggest, Sorell said the phone records were consistent with phone being west of Leongatha and east of Koonwarra.
“If this were a visit to the Outtrim postcode, it would be to the eastern extremity, and it might not even be that far across at this stage. So it is a possible visit,” he said.
“There is a gap in the data for about half an hour. We don’t have any information where that phone is.
“The trends show the phone has moved westwards. So although this is a possible visit into the Outtrim area, it is limited by how much the phone is able to move (in that timeframe).
“Although there is a possibility (of a visit to Outtrim), it is not strongly suggested by the phone records.”
Defence cast doubt on accuracy of digital analysis
Dr Matthew Sorell has commenced cross-examination.
Following on from questioning about Patterson’s mobile data activity on July 31, 2023, defence barrister Colin Mandy SC suggested to Sorell that the phone record analysis identifying a possible visit to Outtrim could also be consistent with his client using her phone at her home.
Mandy: “(You said yesterday) the base station that gives you the best service at the front of your house, may not be the base station that gives you the best service at the back of your house.
“Therefore, a movement even within a house is consistent with the evidence you just gave?
Sorell: “It could be, I would need more information (about the location specifics of the house). But I accept that proposition.”
Digital forensic expert accepts Patterson’s mobile location analysis is not conclusive
Defence barrister Colin Mandy SC has put it to Dr Matthew Sorell that mobile data records are not conclusive.
Mandy: “You said yesterday the best that can be said is that a phone is in a general area, or more convincingly, that a phone is not in a particular area.”
Sorell: “Yes.”
Defence: “So it is easier to disclude the fact a phone has not been in an area, than to conclude a phone has been in a particular area?”
Sorell: “Yes, that is right. They can support that proposition, but they do not prove that proposition.”
Mandy: “To say a phone has been in an area, you would need other corroborating information?”
Sorell: “Yes, that is right.”
‘Many reasons’ why phone may switch between base stations
The court has heard there are many reasons a phone’s data connections may show periodic shifts between base stations.
Under cross-examination, defence barrister Colin Mandy put it to Dr Matthew Sorell that he previously stated there were several explanations for why data connections might shift between networks.
Sorell agreed, confirming contributing factors include weather events, the power of the base station, its height, the antenna tilt (in relation to the ground) or its direction (north, south, west, east etc.), the geography, and topography.
Comparison of data records provide expert ‘confidence’ in Outtrim visit
The defence has questioned Sorell about his analysis that found Patterson’s mobile was in the Outtrim area on May 22, 2023.
The court previously heard that death cap mushrooms were sighted in the Outtrim area on May 21, 2023 and analysis of Patterson’s mobile phone data showed she had travelled there the following day.
Sorell explained to the court on Monday that he used two types of data records - call charge records and event-based monitoring - to perform his analysis.
His first analysis of CCR found that Patterson’s phone had a 13 minute dwell time in the Outtrim area, but he revised his analysis to a 25 minute time period after examining additional EBM information.
Under cross-examination on Tuesday, Mandy asked Sorell questions to clarify his process of analysis.
Sorell explained that while the CCR suggested the phone dwelled at Outtrim between 11.18am and 11.31am, the EBM records made him feel confident that time period actually reflected a journey to the Outtrim area instead.
“When the EBM records became available, my opinion changed.
in and around the northern section of the Outtrim locality from to 11.24am and 11.41am, possibly as late as 11.49am.
Mandy put it to Sorell that having the EBM data allowed him to make more confident opinions, to which he agreed.
Possible Patterson did not travel to Outtrim or Loch in autumn 2023, court hears
The court has been shown a map of the proposed data movement of Patterson’s phone on May 22, 2023, which suggested she “dwelled” in Outtrim.
The court heard that anaylsis was based on Patterson’s phone connecting to the Outtrim base station, which is a dominant base station in that area, multiple times that morning.
The defence suggested to Sorell there were a variety of propositions which may account for that data pattern.
Mandy: “Can I suggest this is consistent with the handset never entering the Outtrim postcode?”
Sorell responded: “There are places outside the Outtrim postcode where these patterns could conceivably come up.”
Defence: “Is it consistent with that possibility?”
Sorell: “It is statistically possible.”
Sorell explained further, detailed analysis would need to be undertaken to draw up those possible scenarios, and confirmed he had not been asked by detectives to perform that type of analysis.
However, he noted he was satisfied from the analysis he did undertake that the handset was travelling throughout the Gippsland region between 11am and midday on May 22, 2023.
Mandy then turned to previous evidence provided by Sorell which suggested Patterson’s phone was in the Loch area twice in autumn 2023 - on April 28 and again on May 22.
That analysis was based on findings that Patterson’s phone appeared to travel through that area on the first occasion then remained stationary in that zone on the second.
Under questioning from the defence, Sorell confirmed he
Digital Forensic expert re-examined
Under re-examination by the prosecution, Dr Matthew Sorell was asked about the possible causes of the absence of data in Patterson’s phone records.
Sorell:“Turning the phone off will actively shut down the data connections.”
Pros: What about (removing) the sim?
Sorell: “If the phone is effectively switched off, the sim removed, and a new sim card inserted, that will turn the data off because the phone has been switched off. “
Sorell said that activity would show an end to a data connection, and it would be reflected in the record.
CCTV shows Patterson made ‘nine-second’ stop to service station toilet
Detective Senior Constable Khuong Tran has taken the stand.
The court has been shown CCTV footage Tran obtained during an investigation into Patterson’s movements following the lunch.
The footage shows Patterson attending a BP service station at Caldermeade on 30 July, 2023 - the day after the lunch.
Dressed in a grey jumper and white pants with a brown bag slung over her arm, Patterson can be shown walking into the BP and straight to the toilets at 3.20pm.
She emerges from the toilets nine seconds later (still at 3.20pm) before looking at sandwiches in a refrigerator.
She then walks over to the cold drinks and confectionery sections to have a look at the goods before making her way to the cash register with an item.
She is then seen exiting the store at 3.22pm, jumping in her car, then driving off.
The court previously heard Patterson reported that she was suffering diarrhoea and nausea in the hours and days after the lunch.
