Citation: R v Wrigley (No 3) [2025] NSWSC 397
Court: Supreme Court of New South Wales
Date: 28 April 2025
Judge(s): Ierace J
Background
An accused man stands trial charged with the murder of a 59-year-old man at a remote rural property near Nyngan on or about 23 January 2023, along with three related charges of theft and disposal of property taken from the deceased's residence. The Crown alleges the accused drove to the property at night, killed the deceased by inflicting blunt force head injuries, stole a Toyota HiLux and a set of Milwaukee-brand tools, then set fire to the HiLux on a backroad in the early hours of the morning and later sold some tools.
The accused lodged a notice of alibi, asserting he spent the relevant period in his Toyota Tarago van parked in bushland outside the Nyngan township, except for a two-hour window when he says he walked into town and back. The Crown sought to counter that alibi in part through expert telecommunications evidence examining two mobile phones the Crown alleges the accused used during the period in question.
The Crown retained Professor Aruna Seneviratne, an electronics engineer with a doctorate in communications systems and extensive professional involvement in telecommunications research, to analyse data from Telstra and Optus cell towers and express opinions about where the phones were located during the relevant hours. The defence challenged the admissibility of significant portions of that evidence.
Legal Issues
- Whether Professor Seneviratne possessed the specialised knowledge, within the meaning of s 79(1) of the Evidence Act 1995 (NSW), to express an opinion that the antenna a mobile phone connected with was in fact the closest available antenna to the phone's location at a given time.
- Whether his opinion that the Telstra phone and the Optus phone were effectively at the same precise location at the same time was based wholly or substantially on his specialised knowledge, or was speculative.
- Whether his opinions as to the consistency or inconsistency of each phone's location data with particular places (including the accused's alibi location) were admissible.
Decision
Issue 1: Probability opinions about phone location consistency
Ierace J admitted Professor Seneviratne's opinions that the mobile phone data was consistent or inconsistent with particular locations, expressed as "likely," "unlikely," or "very unlikely." The defence argued that because several variables, including call congestion, physical obstacles, and network algorithms, can cause a phone to connect with a more distant tower rather than the nearest one, the expert was in no better position than a layperson to assess which tower was truly closest (at [45]-[46]).
His Honour rejected that argument. The expert did not rely solely on azimuth data or a simple assumption of closest-tower connection. He also drew on comprehensive event-based monitoring data recording every interaction between each phone and the network, and his reasoning was transparent and explicable (at [47]). That methodology brought his opinions within the test described by the High Court in Dasreef Pty Ltd v Hawchar (2011) 243 CLR 588, satisfying the court that the opinions were substantially based on his specialised knowledge (at [48]).
Issue 2: Opinion that the two phones were in the same specific location
Ierace J ruled inadmissible Professor Seneviratne's opinion that the Telstra and Optus phones constituted a "single entity" and were effectively at the same precise locations at the same times between 11pm on 22 January and 4.17am on 23 January (at [49]). The expert's stated basis for that opinion was that the two phones repeatedly connected to their respective towers in the same broad geographical area during that period (at [36]).
His Honour was not satisfied that this reasoning was sufficient to ground an opinion that the phones were at the same specific location, as distinct from the same general area. The voir dire evidence did not establish that the opinion was based wholly or substantially on specialised knowledge. In his Honour's view, it was speculative (at [49]).
Orders Made
- Professor Seneviratne's opinions as to the probability of the consistency of particular mobile phones being in specified locations are admissible.
- Professor Seneviratne's opinion that the Telstra and Optus mobile phones were in the same specific location at the same time is inadmissible.
Key Takeaways
-
Under s 79(1) of the Evidence Act 1995 (NSW), an expert telecommunications opinion about the probable location of a mobile phone based on cell tower connection data is admissible where the expert draws on comprehensive network interaction records and explains the reasoning transparently, not merely on the azimuth of the connecting antenna (at [47]-[48]).
-
A recognised risk that network variables such as congestion, physical obstacles, or carrier algorithms may cause a phone to connect with a non-closest tower does not automatically disqualify expert cell tower evidence; the question is whether the expert's specialised knowledge, applied to the totality of available data, provides a sufficiently reliable basis for the opinion (at [45]-[47]).
-
The Supreme Court drew a firm line between an opinion that two phones were in the same general geographical area (which the expert's methodology could support) and an opinion that they were at the same specific, precise location (which it could not), ruling the latter speculative and inadmissible (at [49]).
-
The Dasreef requirement that an expert opinion be based "wholly or substantially" on specialised knowledge applies with equal force to telecommunications evidence: where the bridge between the data and the conclusion is not adequately explained by reference to the expert's specialised knowledge, the opinion will not be admitted (at [48]-[49]).
-
An investigating officer's untested location opinions, included in a briefing document provided to the expert, do not themselves supply the specialised knowledge foundation required for the expert's conclusions; the expert must independently apply their own knowledge to the underlying data (at [21], [47]).
Legislation and Cases Referenced
Legislation
- Evidence Act 1995 (NSW) , s 79(1)
Cases
- Dasreef Pty Ltd v Hawchar (2011) 243 CLR 588; [2011] HCA 21
- Makita (Aust) Pty Ltd v Sprowles (2001) 52 NSWLR 705; [2001] NSWCA 305