How "signal sniffer" technology is being used in the search for Nancy Guthrie

February 18, 2026

TL;DR

A "signal sniffer" tracking device is being used in the search for Nancy Guthrie, who went missing on February 1.
The device detects signals from Guthrie's pacemaker, which uses Bluetooth Low Energy technology.
Former NSA hacker David Kennedy invented the signal sniffer.
The pacemaker's signal was disconnected from her phone at 2:28 a.m.
The detection range of the signal sniffer can be extended to several hundred feet using amplifiers and antennas.
A test demonstrated the device's detection range could be extended to approximately 800 feet.
The tracking tool has been mounted on a helicopter to aid the search.
Kennedy suggests drones are more efficient for signal sniffing than helicopters or cars due to potential signal interference.
Expanding the use of drones and building infrastructure are key to speeding up searches.
Manpower and drone technology are crucial factors in the effectiveness of this search method.

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