The search is ongoing for 84-year-old Nancy Guthrie, the mother of "Today" show host Savannah Guthrie, who investigators say appears to have been kidnapped from her Tucson, Arizona, home in the early hours of Sunday, Feb. 1.
The FBI has released photos and videos of an armed person in a mask in front of her home, appearing to tamper with a security camera.
Anyone with information is urged to call 911 or the Pima County Sheriff's Department at 520-351-4900.
Click here for the detailed timeline of the investigation into Nancy Guthrie's disappearance.
The FBI has reached out to Mexican authorities to make them aware of Nancy Guthrie’s disappearance, law enforcement sources told ABC News.
There is no evidence she was taken across the border, but it’s an avenue investigators are exploring given the proximity to Tucson, Arizona, the sources said.
-ABC News’ Aaron Katersky and Luke Barr
Investigators arrived at Nancy Guthrie’s home on Thursday morning to briefly erect a white tent -- typically used for privacy -- outside her front door.
Investigators took the tent down after about an hour and drove away in unmarked vehicles with a large pelican case labeled "video forensics." They also carried what appeared to be a laser measuring device.
-ABC News' Aaron Katersky
In a new Instagram post on Thursday, Savannah Guthrie shared an old home video from her childhood, showing her and her sister with their mother, Nancy Guthrie. The video is followed by a still photo of all three siblings with Nancy Guthrie.
"[O]ur lovely mom," Savannah Guthrie wrote in the caption. "we will never give up on her. thank you for your prayers and hope."
The Pima County Sheriff's Department is now asking Nancy Guthrie’s neighbors to check their home security cameras for footage from an earlier timeframe than the early morning of Feb. 1, when she was likely abducted.
Investigators on Thursday asked homeowners for video footage from Jan. 11 between 9 p.m. and midnight. They did not specify why.
They also asked for footage from Jan. 31 between 9:30 a.m. and 11 a.m. Authorities said there was a suspicious vehicle on a nearby street around 10 a.m.
The request came through the app Neighbors.
-ABC News' Aaron Katersky
The Pima County Sheriff’s Department and the FBI said on Wednesday they are continuing to follow up on all 18,000 calls to investigators related to the disappearance of Nancy Guthrie.
Up to 4,000 calls to investigators have been made since the FBI released doorbell-camera images and video of an "armed individual" apparently tampering with a security camera at the front door of the 84-year-old woman's house near Tucson, Arizona, authorities said.
"We thank the media and the public for the thousands of tips submitted through the various tip lines," the sheriff's office and the FBI said in a joint statement.
Several hundred detectives and agents are assigned to this case, and authorities said, "You will continue to see increased law enforcement activity throughout Pima County as the investigation expands."
-ABC News' Aaron Katersky
The FBI has reached out to Mexican authorities to make them aware of Nancy Guthrie’s disappearance, law enforcement sources told ABC News.
There is no evidence she was taken across the border, but it’s an avenue investigators are exploring given the proximity to Tucson, Arizona, the sources said.
-ABC News’ Aaron Katersky and Luke Barr
