CriminalUncategorisedForensic Evidence Used in the Erin Patterson Case

Overview

The prosecution in the Erin Patterson case relied heavily on forensic evidence related to digital devices, financial records, and toxicology. The most significant forensic elements presented in court included mobile phone and SIM card activity, factory resets of devices, credit card transactions, and the handling of physical evidence from the scene of the alleged poisonings.

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Mobile Phones and SIM Cards

Alleged Device Manipulation and Evidence Concealment

• SIM Card Swapping: Police alleged that after the fatal lunch, Erin Patterson swapped the SIM card from her primary phone into a different device (a Nokia phone). The original SIM card from a Samsung tablet was also placed into another phone, referred to as “phone B” by investigators1.

• Factory Resets: The phone handed over to police by Patterson was allegedly wiped (factory reset) three times after the lunch and before being surrendered. This phone contained a SIM card that had seen little use for calls or messages, suggesting it was not her regular phone13.

• Missing Primary Phone: Police stated that Patterson’s primary phone, believed to be central to the investigation, was never recovered. The device handed to police was described as a secondary phone, and a third device with older messages was also found in her home1.

• Remote Wipe: Evidence was presented that one of the phones was remotely wiped on August 6, the day after it was handed to police, further complicating forensic recovery efforts3.

Digital Forensics Testimony

• Victoria Police digital forensics officer Shamen Fox-Henry detailed the analysis of the seized devices, including the discovery of multiple factory resets and the recovery of messages that prosecutors argued showed motive or state of mind34.

• The forensic analysis also included examination of internet searches and visits to web pages about death cap mushrooms on devices seized from Patterson’s home4.

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Credit Card and Financial Records

• Purchasing Evidence: The prosecution presented Patterson’s bank records, shopping receipts, and even Woolworths rewards points data to track her purchases in the week leading up to the fatal lunch. This included receipts for ingredients such as mushrooms and filo pastry, as well as a restaurant receipt showing her name and address1.

• Transaction Tracing: A specific dinner purchase was highlighted, with the receipt showing it was paid for using a Visa credit card linked to Patterson, and her name appearing in the transaction ID field1.

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Forensic Toxicology and Physical Evidence

• Leftover Food Samples: The case against Patterson was also built on toxicological testing of leftovers from the lunch, which tested positive for death cap mushroom toxins2.

• Chain of Custody Issues: The defense challenged the reliability of this evidence, pointing to procedural flaws such as the combining of samples from different locations in the home into a single bag, and a month-long delay before the samples reached the forensic laboratory. These chain of custody issues were acknowledged by prosecution experts and are expected to be central to any appeal2.

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Summary Table: Key Forensic Evidence

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Conclusion

The prosecution’s case relied on a combination of digital forensics (including alleged manipulation of phones and SIM cards, factory resets, and internet search history), financial records tracing Patterson’s purchases, and toxicological analysis of food samples. However, significant questions about the integrity of the physical evidence—especially regarding the chain of custody—have created vulnerabilities that the defense is expected to pursue in appeals2. The handling of mobile phones and credit cards was central to the prosecution’s narrative of intent and concealment13.