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Maryland departments test system that tracks wireless signals from vehicles
A new police tool called SignalTrace can detect Bluetooth, Wi-Fi and other signals from devices in passing vehicles. Prince George’s County is piloting it, while Harford County says it is still researching the technology and has no deployment timeline.
Maryland police agencies are considering a surveillance tool that goes beyond reading license plates: SignalTrace detects wireless signals from phones and other personal devices in passing vehicles.
Prince George’s County Police are piloting the system, while the Harford County Sheriff’s Office says it is researching the technology but has not set a date for deployment. The information was reported Oct. 26, 2026.
SignalTrace is sold by a company that supplies license-plate readers to police departments across central Maryland. The company says its system can build a “digital fingerprint” of devices that regularly travel together, using Bluetooth, Wi-Fi and other wireless signals.
A civil liberties advocate has argued that police should not use the technology. Its ability to identify devices linked by repeated travel raises questions about how law enforcement might collect and use information about people who are not suspected of a crime. The available information does not specify what safeguards, retention limits or rules would govern the data.
The contrasting positions in Prince George’s and Harford counties leave residents with different levels of certainty: one department is testing the system, while the other has not committed to putting it into operation.