The conviction of Erin Patterson for three murders and one attempted murder has produced one of the most closely scrutinised criminal appeals in Australia. At the centre of part of that appeal is an increasingly familiar form of forensic evidence: mobile-phone location data.
Patterson was convicted in July 2025 of murdering Don and Gail Patterson and Heather Wilkinson after serving them a beef Wellington containing lethal death cap mushrooms at a lunch at her home in Leongatha, Victoria, in July 2023. She was also convicted of attempting to murder Heather’s husband, Ian Wilkinson, who survived after a prolonged illness and liver transplantation. Patterson received a life sentence with a 33-year non-parole period. She has maintained that the poisoning was accidental. The Victorian Court of Appeal heard her conviction appeal in August 2026, while the prosecution separately challenged the length of the non-parole period. The court has reserved its judgment.
However, for expert witnesses, the case is of great interest because the prosecution’s circumstantial case included an unusual combination of digital evidence, telecommunications analysis and evidence concerning the locations where death cap mushrooms had been discovered.
Dr Matthew Sorell: The Telecommunications Expert Witness
One of the most significant expert witnesses was Dr Matthew Sorell, a telecommunications and digital-forensics specialist.
Sorell is a Senior Lecturer at Adelaide University and has a professional background extending across telecommunications, multimedia and computer systems engineering. His university profile identifies digital forensic science as his principal research field. He has also been Director and Chief Technology Officer of Digital Forensic Sciences Australia since 2022. His qualifications include a PhD in Information Technology from George Mason University, a Bachelor of Engineering in Computer Systems with First Class Honours and a Bachelor of Science in theoretical and experimental physics from the University of Adelaide. His university biography also identifies expertise in telecommunications, mobile technology and forensic investigation techniques for multimedia and computer data.
That combination of engineering, telecommunications and forensic experience made him inherently well suited to explain mobile-phone evidence to the trial judge and jury.
Sorell was instructed to analyse approximately four years of telecommunications records relating to a phone number associated with Patterson. His task was not to determine guilt, nor could the data establish with precision where Patterson herself was located. His role was to analyse the telecommunications evidence and explain what could reasonably be inferred from the handset’s connections with mobile-phone infrastructure.
The evidence became significant because the phone appeared to have been in or around two small Victorian communities—Loch and Outtrim—where death cap mushrooms had recently been reported in the press.
What the phone evidence showed
According to evidence reported during the trial, Patterson’s phone connected to a Loch South base station for approximately 43 minutes on the morning of 22 May 2023. It subsequently connected almost exclusively to the Outtrim base station for about 25 minutes. Sorell told the court that the pattern was consistent with the phone being relatively stationary during the Outtrim period. (ABC News)
The evidence also identified a possible earlier visit to Loch on 28 April 2023. Sorell said the telecommunications records were consistent with the possibility that the phone remained in the Loch area for approximately 45 minutes, although he expressly acknowledged limitations in attempting to establish an exact location or the actions of the person carrying the device. (The Guardian)
That qualification is crucial. A mobile telephone does not function as a miniature GPS tracker simply because it connects to a particular cell tower. Base stations cover geographical areas, and a handset can sometimes connect to infrastructure outside the immediate location one might assume from the tower’s name. Sorell accepted that the technology could not establish an exact address, nor could it prove what the phone’s owner was doing; thus, the evidence was presented as establishing possible visits or opportunities, rather than proving that Patterson physically stood at a particular mushroom patch.
The Crown nevertheless argued that the telecommunications evidence became significant when considered alongside the mushroom sightings and other circumstantial evidence.
The mushrooms: from citizen science to courtroom evidence
The mushroom evidence was unusual in its origin.Two important death cap sightings had been recorded on iNaturalist, a citizen-science platform on which members of the public and specialists can upload observations of plants, fungi and animals.
Christine McKenzie, a retired pharmacist and former poisons-information specialist, told the trial that she discovered death cap mushrooms near Loch on 18 April 2023. She photographed the mushrooms and uploaded the observation to iNaturalist. She subsequently removed mushrooms from the area because she was concerned that somebody might mistake them for an edible species.
Then came evidence from Dr Tom May, a prominent fungi expert. May told the court that he personally discovered death cap mushrooms near Outtrim in May 2023 and uploaded his observations to iNaturalist on 21 May. His post contained photographs and precise geographical coordinates identifying the location, including an area around Neilson Street. (ABC News)
The significance for the prosecution was timing. The Crown alleged that Patterson’s phone subsequently appeared in the same general areas. The phone was recorded in the Loch region on 28 April, shortly after McKenzie’s death-cap observation. On 22 May, one day after May’s Outtrim posting, the phone was recorded in the Loch and Outtrim areas. The prosecution relied on that sequence as circumstantial evidence supporting its contention that Patterson had deliberately sought out death cap mushrooms.
The defence disputed that inference.
The appeal challenge
The mobile-phone evidence has now become one of the grounds of Patterson’s appeal. Her lawyers argued before the Victorian Court of Appeal that the telecommunications evidence was excessively technical and insufficiently precise. They contended that objective telephone-network information had effectively been converted into a subjective inference about Patterson’s movements. They also challenged the combination of the tower evidence with the iNaturalist mushroom sightings, arguing that the material was unfairly prejudicial.
The prosecution rejected that characterisation. Its argument was that Sorell had not manufactured evidence from nothing; he had applied his specialist expertise to objective telecommunications records and expressed an expert opinion about what those records indicated.
The prosecution also emphasised that the unusual phone activity mattered. According to the Crown, the possible trips to Loch and Outtrim were outliers when compared with the much larger period of phone records examined by the expert witness.
This distinction underpins an important principle of expert evidence. The expert does not decide the ultimate issue for the court. Rather, the expert provides technical assistance enabling the tribunal of fact to understand evidence that falls outside ordinary knowledge.
Why the evidence matters
Sorell’s evidence did not, by itself, demonstrate that Patterson harvested death cap mushrooms. Its importance lay in the convergence of evidence.
The prosecution presented mushroom sightings, online activity, telecommunications records, evidence concerning a food dehydrator and other digital and physical evidence as parts of a broader circumstantial case. The Crown argued that the individual pieces acquired greater significance when viewed together.
For the defence, however, the danger was that the jury might move too quickly from “the phone was probably in this general area” to “Patterson was there collecting mushrooms.” That is precisely the inferential gap an expert must guard against.
The case therefore offers an important lesson for expert witnesses working in digital forensics. A technically sophisticated dataset does not automatically produce a precise conclusion. The expert must identify the limitations of the methodology, distinguish established facts from probabilities and avoid allowing an inferential conclusion to become stronger than the underlying data warrants.
The Court of Appeal must now determine whether the trial judge properly admitted and explained this evidence and whether its use, considered alongside the other challenged evidence, resulted in a miscarriage of justice.
The appeal was heard in August 2026 and judgment has been reserved. The prosecution has also appealed the sentence, arguing that the 33-year non-parole period was manifestly inadequate and seeking a sentence that would stop Patterson from obtaining parole.
Whatever the eventual outcome, the Patterson litigation provides a compelling case study in modern expert evidence. Mobile-phone records, citizen-science databases and specialist mycology may appear to belong to entirely different evidential worlds. In this prosecution, they became interconnected.
by Edward Gordon Price
- Death Cap Mushrooms, Amanita phalloides: Wikipedia
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