Authorities searching for Nancy Guthrie are deploying a piece of specialized tracking technology — commonly referred to as a “signal sniffer” — in an effort to detect emissions from her implanted pacemaker as the investigation intensifies in Tucson, Arizona.
Here’s what that device is—and how it works.
What is a ‘signal sniffer’?
A signal sniffer is a radio-frequency (RF) detection device used to locate electronic signals emitted by wireless equipment. Law enforcement and search teams typically use such technology to:
-Detect radio transmissions
-Identify wireless communication devices
-Track signal sources within a defined range
In this case, authorities mounted the device on a helicopter operated by the Pima County Sheriff’s Department, which was seen flying low over residential areas, as per reports.
The goal: determine whether Guthrie’s pacemaker is emitting any detectable signal that could help narrow the search area.
Can a pacemaker be tracked?
Pacemakers are small, battery-powered devices implanted under the skin to regulate heart rhythm. They do not function as GPS trackers.
However, modern pacemakers can:
-Wirelessly transmit medical data
-Connect to a bedside home monitor
-Sync with smartphone or smartwatch apps
-Alert heart clinics about serious cardiac events
But there are limitations:
-The device must be within range of its paired home monitor or smartphone
-It cannot transmit location data
-It cannot independently broadcast a tracking signal
-It cannot communicate without being connected to a monitoring system
Importantly, even if disconnected from an app — as authorities say Guthrie’s was shortly before she went missing — the pacemaker continues performing its core medical function.
Context of the search
Nancy Guthrie, 84, was reported missing February 1 after last being seen at her home in Pima County. Authorities believe she was abducted.
The case has drawn national attention, including comments from Donald Trump, who said “progress has been made” in the investigation.
The sheriff’s department has received nearly 18,000 tips, released images of a masked suspect, and doubled the reward to $100,000 for information leading to her recovery or an arrest.
The FBI has also released photos and video tied to the case. The search remains ongoing.
