Toyah Cordingley murder trial: Experts called to explain mobile phone data evidence
Police used mobile phone data to identify about 70 cars near Toyah Cordingley’s mobile phone but now that data has come under questioning at her murder trial.
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The accuracy and reliability of the mobile telephone data used to plot the movement of Toyah Cordingley’s mobile phone on the afternoon of her death is emerging as critical information in the trial of Rajwinder Singh, 40, accused of her murder.
Mr Singh, a former nurse from Innisfail, has pleaded not guilty in the Cairns Supreme Court to the murder of Ms Cordingley, 24, at Wangetti Beach on October 21, 2018.
During the trial, the court has been told Ms Cordingley’s phone was moving towards Cairns at a time when her car was still at Wangetti Beach, “pinging” cell towers at Smithfield and Saddle Mountain.
The court has been told “timing advance” data can be used to identify the location of a mobile phone relative to the base station it is “pinging”, with a distance measurement calculated from the signal, and its angle determined by the part of the cell tower that is activated.
A Professor from the University of New South Wales, School of Electrical Engineering with more than 40 years of experience in telecommunications, research, and teaching in Australia, England, France and Sweden, was called to give evidence to the court on Tuesday.
Professor Aruna Seneviratne gave evidence about the way mobile phones and cell towers work.
He said mobile phone radio signals will weaken as they travel greater distances, and can “bounce off things” and be affected by obstacles in their path.
Investigating officer, Detective Sergeant Matt Mattock, was in charge of identifying all cars whose movements were similar to Toyah Cordingley’s mobile phone, told the court “timing advance” data from Telstra had been used to narrow the time frames and locations of focus.
Under cross examination by defence barrister Angus Edwards KC, Sergeant Mattock said certain cars were eliminated from the investigation and others chosen for a closer focus based on this data.
Sergeant Mattock said his team focused their investigations on a spreadsheet of 70 cars captured on a Transport and Main Roads camera, travelling south through Clifton Beach in a 16-minute window of time between 4.54pm and 5.10pm.
“The spreadsheet relies heavily on the accuracy of timing advance,” questioned Mr Edwards, to which Sergeant Mattock answered “correct”.
“If timing advance is out by several minutes, or several hundred metres, that would completely change your focus of this investigation?” Mr Edwards asked.
Sergeant Mattock replied that: “Several hundred metres would not have changed the windows of time that I have chosen because I have gone broader.”
He said a number of cars were excluded from further investigation because they passed through key locations seconds before or after the chosen time frame.
Other cars were excluded when their drivers came forward to the police.
Sergeant Mattock said police issued a media call-out to the public for the drivers of 70 cars to come forward as part of the investigation.
Around half of the drivers made themselves known to the police, and were interviewed and were excluded.
Mr Edwards asked Sergeant Mattock about a number of cars whose drivers were not found or that were not further investigated, including a grey silver Hyundai hatchback and a white Holden Barina hatchback that passed by “right on the cusp” of the time range on which investigators were focusing.
Earlier in the trial, the court was told the driver of the blue Alfa Romeo did not come forward to the police.
Mr Edwards also asked Sergeant Mattock about a CCTV camera at Ellis Beach Bar and Grill, which did not capture the blue Alfa Romeo that day.
Sergeant Mattock explained the CCTV camera at Ellis Beach was movement activated, so did not capture all the cars passing that point.
Brisbane-based homicide detective Sergeant Adam Riley also took the stand on Tuesday to speak about a series of maps he created, some titled “Telstra sectors activated by deceased’s phone”, to assist with the investigation.
More than 20 maps of areas from Innisfail to Wangetti Beach were tendered, with Sergeant Riley noting they incorporated timing advance data, the location of mobile phone cell towers, CCTV timing data, and the paths of both the blue Alfa Romeo vehicle of interest, and Ms Cordingley’s phone, which was illustrated on the maps as a blue arc.
He also mapped mobile phone data relevant to two men – Evan McCrea and Remy Fry – who have been named earlier in the trial as “possible other suspects”.
Under cross examination, Sergeant Riley said he was not instructed to create maps for any cars other than the Alfa Romeo.
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Originally published as Toyah Cordingley murder trial: Experts called to explain mobile phone data evidence
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