What is a “signal sniffer”? Police use rare technique to find Nancy Guthrie; here’s the latest

“Investigators used a so-called ‘signal sniffer.’ It was a small device that was delivered and attached to the Sheriff’s helicopter. It could detect Nancy Guthrie’s pacemaker signal. The helicopter had to stay low and move slowly to work,” Entin wrote on X .

The search entered its third week on Sunday, February 14, with a team awaiting forensic results from a late-night operation on Friday, which took place just a few miles from Nancy’s home. Four people were detained and later released after the FBI executed a federal search warrant at a home in Catalina Foothills, officials told Fox News Digital on Saturday.

Nanos, who was not present during the search, said no one was arrested and “no sign of Nancy was found.”

Signal sniffers are police’s latest hope in the Guthrie case. Authorities used equipment mounted on a helicopter to try to detect Nancy’s pacemaker, NewsNation reported.

Learn more | Nancy Guthrie suspect found? A manhunt is underway in Tucson, Pima County.

The technology was used on the skid of a Pima County Sheriff’s Department helicopter in Arizona, which was seen flying low over the Tucson area.

Former FBI agent Maureen O’Connell said the agency may use a variety of techniques to find Nancy. “Regarding this particular tool… I do know that pacemakers sound very short range alarms, or whatever, so they have to be very close,” O’Connell told NewsNation on Saturday.

Learn more | Where is Anne Guthrie? Hours after the video of the subject was released, police conducted a search warrant in the Tucson neighborhood where Nancy’s daughter lives.

Hours later, authorities arrived at Nancy’s Arizona home around noon and found her phone and Apple Watch still inside, sources said.

Nanos previously told Us Weekly that Nancy’s disappearance was “difficult” for Savannah and her siblings, sister Anne and brother Camron. “They rely on each other,” Nanos said. “They’ve been very cooperative with us and everything we do.”