PIMA COUNTY, Ariz. -- The search for 84-year-old Nancy Guthrie, the mother of "Today" host Savannah Guthrie, began after she was abducted from her home near Tucson, Arizona, on Sunday, Feb. 1, authorities said.
The Guthrie family has made multiple public pleas for any information surrounding their missing mother.
On Feb. 10, the FBI released an updated missing person poster that includes images of a potential subject from newly released doorbell camera video.
Anyone with information is urged to call 911 or the Pima County Sheriff's Department at 520-351-4900.
Investigators believe Nancy Guthrie was abducted in her sleep early on Feb. 1, according to the sheriff's department.
1:47 a.m.: Nancy Guthrie's doorbell camera disconnected, the sheriff said.
2:12 a.m.: The camera software detected a person on camera, but no video is available, the sheriff said.
11:56 a.m.: Relatives responded to Nancy Guthrie's home and discovered she was missing, the sheriff said.
12:03 p.m.: The family called 911, the sheriff said.
Click here for a full timeline of the case.
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.
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."
