The FBI and Pima County Sheriff’s Department brought in drone technology by Parsons Corporation to try to locate Nancy Guthrie using signals from her pacemaker, sources told ABC News. The technology, called BlueFly, was deployed to aid the search at the beginning of February, according to sources familiar with the investigation.

BlueFly can detect the presence of Bluetooth low energy and Wi-Fi signals, identify the devices present and localize the devices based on the signal strength relative to the position of the drone, according to the company’s website. Parsons said in a statement to ABC News, "BlueFly® is a Bluetooth and Wi-Fi sensor intended for search and rescue operations in challenging environments. The technology can -- and has been -- used on a variety of air (drones, helicopters, etc.), ground vehicles, and on foot.”

Separately, the FBI canvassed gun shops in the Tucson, Arizona, area early last week as part of the investigation.

The suspect seen on Guthrie’s doorbell camera appeared to be armed with a holstered pistol and the authorities are looking to identify the gun and the holster, as well as where those items were sold.

-ABC News’ Aaron Katersky

DNA from the glove recovered near Nancy Guthrie’s home remains at a private lab in Florida, where the Pima County Sheriff’s Department sent it on Feb. 12, law enforcement sources told ABC News.

The sample is still undergoing quality control tests before the FBI hopes to run it through CoDIS in the “near future,” the sources said.

-ABC News' Luke Barr and Aaron Katersky

Pima County Sheriff Chris Nanos said Monday that members of the Guthrie family are “cleared” as suspects in Nancy Guthrie’s disappearance.

“To be clear … the Guthrie family -- to include all siblings and spouses -- has been cleared as possible suspects in this case,” the sheriff said in a statement. “The family has been nothing but cooperative and gracious and are victims in this case.”

“The Guthrie family are victims plain and simple,” the statement said.

ABC News previously reported that, according to law enforcement sources, investigators were leaning away from the Guthries as suspects.

-ABC News’ Aaron Katersky

The Pima County Sheriff’s Department said it's possible the suspect in Nancy Guthrie's kidnapping may have purchased the clothes he’s seen wearing on the surveillance camera at Walmart, but that clothing is not exclusively available at Walmart.

Investigators last week were working to trace the point of sale of the suspect’s backpack, which was sold at Walmart.

Meanwhile, the FBI is focused on the unknown male DNA from a glove found about 2 miles from Nancy Guthrie’s home.

The FBI said it received preliminary results on Saturday. The FBI said on Sunday it was "awaiting quality control and official confirmation" before putting unknown male profile into the Combined DNA Index System, the national database known as CODIS.

The glove with the DNA profile "appears to match the gloves of the subject in the surveillance video," the FBI said.

-ABC News’ Aaron Katersky