Video has been released of an armed man in a ski mask tampering with the doorbell camera at the Arizona home of US TV journalist Savannah Guthrie's elderly mother shortly before she was abducted.
The footage was released hours before another major break in the search for 84-year-old Nancy Guthrie - the first known arrest in the case following days in which investigators reported making little progress.
The Pima County Sheriff's Department said in an online statement on Tuesday night that its deputies had “detained a subject during a traffic stop” south of Tucson and that the person was “being questioned in connection to the Nancy Guthrie investigation.”
Police have begun searching the home of the person detained, according to sources who spoke to CBS.
The victim was last seen on the night of January 31, when her family dropped her off at her home after dining with her. Relatives reported her missing the following day, according to the sheriff's department, after she failed to show up for Sunday church services.
Hours before the suspect was detained, the FBI and sheriff's office released video footage captured outside Nancy's front door by a Google Nest camera and recovered only after analysts managed to sift through leftover data that had been disposed of in a “back-end” digital repository.
The images, videos and still photos, show a man wearing a woolen ski mask, gloves, a backpack and a gun in a holster. He approaches Nancy's front door in the early hours of February 1, about the time she was abducted.
At one point in the video, the masked figure is seen trying to obscure the camera with foliage gathered from nearby, then appears to damage the camera. The individual’s head is down as he approaches the door, suggesting an awareness of the camera's location, according to a law enforcement source.
Facial hair is visible through the ski mask cut-out around the man's mouth.
Sheriff Chris Nanos has said the camera was disabled shortly before 2am local time on February 1, that Ms Guthrie's pacemaker became disconnected from her phone about a half-hour later, and that she was presumably taken from the house by force.
Traces of blood found on the front porch were confirmed by DNA tests to have come from Nancy, officials said last week. Law enforcement and family members have described her as being of limited mobility, in frail health and in need of daily medication to survive.
TV host Savannah shared the new video on Instagram. "Someone out there recognises this person," she said on Tuesday. "We believe she is still out there. Bring her home."
She said on Monday that her family believes their mother is still alive and issued a new appeal to anyone with information.
The footage marks the first major breakthrough in a case that has gripped the country for more than a week.
Authorities believe Nancy was taken against her will from her house just outside Tucson.
The FBI this week began posting digital billboards in major cities from Texas to California.
Connor Hagan, a spokesperson for the FBI, said on Monday that the agency was not aware of ongoing communication between Ms Guthrie's family and the suspected kidnappers. Authorities also had not identified any suspects or persons of interest, he said.
"Someone has that one piece of information that can help us bring Nancy home," he said.
Authorities have released few details about who may have abducted the 84-year-old from her home in Arizona and whether she is still alive, leaving it unclear if ransom notes demanding money with deadlines already passed were authentic and whether the Guthrie family has had any contact with the abductors.
The FBI is offering a $50,000 (£36,000) reward for any information.
White House Press Secretary Karoline Leavitt said President Donald Trump has reviewed the footage. She said he encouraged people with any information to contact authorities.
"The prayers of this entire White House are with Savannah and her family at this time. We hope this person is found soon and her mother is brought home safely," she said.
