ActivePaper Archive MOBILES MAY HOLD KEY TO UNLOCKING CASE - The West Australian , 11/2/2021



A phone tower at Point Quobba.

New phone towers could yield important details for detectives in the search for little Cleo’s suspected abductor

Unremarkable phone masts like this, in the middle of nowhere, are the only features of the remote and rugged terrain seemingly on the side of detectives.

With the odds stacked against them, investigators have welcomed one lucky break — three modern mobile base stations not far from the coastal location where Cleo Smith vanished in the early hours of October 16.

One of the Telstra towers is at Point Quobba, just a couple of kilometres away. Up to late 2018, when the masts were installed, the stretch of coastline north of Carnarvon was a dead zone for mobile phone coverage.

Despite its remoteness, campers and caravanners at the Blowholes enjoy a better signal — thanks to both a 3G and a 4GX service — than many receive in Carnarvon, the nearest town, 75km south.

For Taskforce Rodia detectives, the modern phone masts are high-tech informants, providing useful metadata to help trace potential suspects and witnesses, as well as verify statements and check alibis.

First and foremost, it can help them identify people who were in the vicinity of the camp site within the crucial time frame.

These could be individuals who haven’t yet come forward, despite all the publicity and pleas for them to do so.

Like other police forces around the world, WA Police routinely requests “cell dumps” or “tower dumps” from Telstra and other telcos to help them solve serious crimes. On getting these requests, that don’t require a warrant, the telco has to download and hand over all of the numbers that bounced off its masts within the specified time frame. Police can then do subscriber checks on all of those numbers to identify the owners.

Evidence obtained can be combined with other evidence, such as CCTV, call data records. and other information. It can also track the path of a mobile phone as it moves from location to location.

Philip Branch, associate professor in computer systems engineering at Swinburne University of Technology, said “most people do not appreciate just how chatty their mobile phone is”. “When a mobile phone is switched on, there is a constant dialogue between it and the network, even without a call being made,” he explained in The Conversation.

“In particular there is a constant exchange of data as to which cell the device is currently located in and which base station it should be connected to.

“If a signal becomes too weak because we have moved out of the cell, or if the current base station we are connected to becomes too congested, the phone connection may be handed over to another base station.

“The data exchanged as part of this process can be of great use to law enforcement agencies. At the very least it can tell an investigator which cell the mobile device was located in at a particular time. But if the investigator is prepared to analyse the data, much more accurate location information can be obtained.

“Since most base stations use directional antennae, the base station can give a good estimate as to the location of the mobile.

“Multiple base stations may be monitoring the signal strength, making it possible for an investigator to pinpoint the location of the mobile to a particular house.”

There’s a lot of detailed and time-intensive work to be done by detectives once they get their hands on the metadata, but in the absence of many leads, it is an essential undertaking. Cell dumps have been likened to “fishing expeditions”, but they’ve proved their worth and netted vital clues in many other cases. Cell phone pings helped Victoria Police catch the killer of Jill Meagher in Melbourne in 2012.

Wi-Fi, Bluetooth and GPS data can establish a phone’s location as well, with more precision than cell site location information. Smartphones store this data until the user takes steps to clear it. Police can request this information from companies such as Google through subpoenas, court orders, or search warrants.

Third-party applications that use location data, such as mapping applications, store users’ location data and transmit it back to the application’s servers, where it is stored until the user takes steps to clear the data.

with Phoebe Pin