What is a “signal sniffer?” It is a device that tracks pings from bluetooth and WiFi devices that is being used to try and find Nancy Guthrie’s pacemaker. The 84-year-old mother of “Today” show co-host Savannah Guthrie was reported missing when she failed to show up for church on Feb. 1, after vanishing in the middle of the night from her home in Tucson, Arizona, in an apparent abduction. CBS News’ Andres Gutierrez is in Tuscon, where he saw a helicopter flying low over Guthrie’s home earlier this month. He later learned the chopper had BlueFly technology – also called a “signal sniffer” – by Parsons Corporation. Here’s what we know about the device and how it works. #tuscon #arizona #news