Authorities are using advanced Bluetooth detection technology as part of the search for Nancy Guthrie, who has been missing for two weeks.

A Pima County Sheriff’s Department helicopter has been flying in a low, methodical grid pattern over the Tucson area near Guthrie’s home in an effort to detect a signal from her pacemaker, according to Fox News. Investigators are using specialized equipment capable of identifying nearby Bluetooth-enabled devices.

Guthrie was last seen around 9:30 PM on January 31 and was reported missing February 1. According to reports, her pacemaker disconnected from its companion phone app shortly before 2 AM on February 1. Around the same time, her Nest home security camera also went offline.

Former FBI special agent Maureen O’Connell told NewsNation that pacemaker-related detection tools typically operate at a short range, meaning search crews would need to be in close proximity to pick up a signal.