Nancy Guthrie kidnapping case: How investigators are using a 'signal sniffer' to track Nancy's pacemaker signal

Investigators searching for Nancy Guthrie are deploying advanced signal-detection technology as the case enters its third week. The device, known as a “signal sniffer,” is designed to locate electronic signals emitted by nearby devices, including Guthrie’s pacemaker. David Kennedy, a former NSA hacker and creator of the signal-sniffing tool, explained to CBS News that Guthrie’s pacemaker likely uses Bluetooth Low Energy (BLE). Authorities determined the device disconnected from its companion phone app at 2:28 am, suggesting the pacemaker continues to transmit a low-power Bluetooth signal intended to conserve battery life for years.

Guthrie, the 84-year-old mother of “Today” co-host Savannah Guthrie, disappeared overnight from her home in Tucson after failing to attend church on Feb. 1. Officials are treating the case as a suspected abduction. Kennedy said Bluetooth Low Energy typically operates within a 10- to 15-foot range. However, by incorporating amplifiers and high-gain antennas, the detection distance can stretch hundreds of feet. In a home experiment using a modified consumer drone and standard equipment, he was able to detect signals from as far as 800 feet away.

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According to Kennedy, aerial deployment dramatically improves coverage. He noted that helicopters or drones equipped with the technology can scan large areas and then narrow in on a signal to within just a few meters. Because the pacemaker emits a signal every two to three minutes, investigators can potentially track its location in intervals.

Law enforcement sources told CBS News that the device was mounted on a helicopter earlier this week. The aircraft reportedly flew at low altitude over areas of interest in hopes of capturing a signal tied to Guthrie’s pacemaker.

Kennedy described the helicopter operation as a rapid response method to gather initial data. While drones may be more efficient for sustained searches due to their maneuverability and speed, helicopters and vehicles can face signal interference from dense structures such as metal buildings and concrete barriers. He added that signal-sniffing technology remains relatively new in law enforcement operations.

Agencies currently lack large drone fleets dedicated to such searches, meaning manpower and equipment limitations could slow efforts. Kennedy estimated that deploying 50 to 60 drones, each covering between 300 and 800 feet, could significantly accelerate the search, potentially reducing coverage time for a 120-square-mile area to a matter of days rather than weeks. Ultimately, he said, the pace of progress depends on available drone operators, technology, and coordination on the ground.