The FBI this week confirmed it is probing suspicious cyber activity as part of its investigation into Nancy Guthrie's disappearance.
The agency, in a notification to members of Congress, said it's looking into whether the perpetrator used sophisticated techniques to exploit certain security controls.
This includes a pen register, according to the FBI, which is a common surveillance tool that typically allows law enforcement to log phone numbers dialed by a particular line.
“The affected system is unclassified and contains law enforcement sensitive information, including returns from legal process, such as pen register and trap and trace surveillance returns, and personally identifiable information pertaining to subjects of FBI investigations,” the notification stated.
The agency, in a statement, confirmed the probe but declined to release further details.
“The FBI identified and addressed suspicious activities on FBI networks, and we have leveraged all technical capabilities to respond,” it said. “We have nothing additional to respond.”
The 84-year-old mother of "Today" show host Savannah Guthrie has been missing for more than a month. She was last seen by a family member at her home on Jan. 31 and reported missing Feb. 1.
Savannah Guthrie on Thursday made an off-camera appearance at the NBC studios to thank colleagues for their support.
The case has garnered national attention as authorities have come up empty on any strong leads.
In a recent update, the Pima County Sheriff's Office said black gloves found two miles from her home were tested but traced back to a restaurant employee who has since been cleared from the case.
"That individual is not part of this investigation," the sheriff's office said, adding that lab analysis remains ongoing for other DNA evidence.
“We also know that she may be lost,” Savannah Guthrie said in a video posted to Instagram. “She may already be gone. She may have already gone home to the Lord that she loves and is dancing in heaven with her mom and her dad and with her beloved brother Pierce and with our daddy. If this is what is to be, then we will accept it.”
Separately, an additional $102,500 is being offered through Tucson Crime Stoppers, along with the FBI’s $100,000 reward.
The suspect in the case has been described by the FBI as a male, approximately 5’9” to 5’10”, with an average build. In published images showing the man at Guthrie's front door, he is wearing gloves and a black, 25-liter Ozark Trail Hiker Pack backpack.