What Happened Each Day Of Nancy Guthrie's Disappearance

New surveillance video of a masked and apparently armed person on Nancy Guthrie's doorstep the night she went missing was released Tuesday by federal investigators.

It's the first major break in the intensifying search for the 84-year-old mother of “Today” show host Savannah Guthrie. Authorities are seeking help identifying the person in the video.

No suspects or persons of interest have been identified, but authorities detained someone south of Tucson on Tuesday for questioning in the case.

It's been more than a week since investigators believe Nancy Guthrie was abducted from her home in Arizona.

Her children have made heartbreaking video pleas for help and the case has drawn national attention. Two deadlines in purported ransom notes sent to the media have come and gone, but it's unclear of there's been any contact with the abductors or if Nancy Guthrie is still alive.

Here is a timeline of events:

5:32 p.m. — Nancy Guthrie takes an Uber to her family's home for dinner.

9:48 p.m. — Guthrie is dropped off at her Tucson, Arizona, home by a family member. The garage door opens and closes minutes later.

1:47 a.m. — The doorbell camera is disconnected.

2:12 a.m. — The camera's software detects movement. Investigators initially said that there was no video available since Guthrie didn't have an active subscription to the company. But digital forensics experts kept working to find images in backend software that might've been lost, corrupted or inaccessible.

2:28 a.m. — Her pacemaker app disconnects from her phone.

11:56 a.m. — Her family checks on her after learning she did not attend church.

12:03 p.m. — The family calls 911 to report a missing person.

12:15 p.m. — Investigators arrive and launch a search operation, including the use of drones and search dogs.

6:46 p.m. — The Pima County Sheriff's Department posts on social media to announce Guthrie's disappearance.

Authorities announce in the morning that they believe Guthrie was kidnapped, abducted or otherwise taken against her will.

KOLD-TV says it received an email Monday night that appears to be a ransom note. The note includes a demand for money with a deadline set for 5 p.m. Thursday and a second one for Monday, investigators said.

Savannah Guthrie posts a message on Instagram on Monday night asking for people's prayers.

A person familiar with the investigation tells The Associated Press that investigators found signs of forced entry at Nancy Guthrie's home.

President Donald Trump tells reporters that the situation is “terrible.”

After turning back Guthrie's property to her family earlier in the week, authorities return to the home for a “follow-up investigation.”

That evening, Savannah Guthrie posts a video on social media in which she tells her mother's kidnapper that her family is ready to talk but wants proof their mom is alive.

Officials reveal that a DNA test of blood found on the home's front porch showed it came from Nancy Guthrie.

The FBI offers a $50,000 reward for information about Guthrie's whereabouts.

Tucson TV station KOLD receives a new message, via email, tied to the Guthrie case. The station says it can't disclose its contents. The FBI says it's aware of a new message and is reviewing its authenticity.

Investigators return to Guthrie's neighborhood to gather more evidence. The president of the Catalina Foothills Association, a neighborhood group, thanks residents in a letter for being willing to speak with law enforcement, share camera images and allow their properties to be searched.

Savannah Guthrie releases another video on social media directly engaging with her mother's potential abductors.

“We received your message, and we understand. We beg you now to return our mother to us so that we can celebrate with her,” she said, flanked by her siblings. “This is the only way we will have peace. This is very valuable to us, and we will pay.”

Detectives and FBI agents do follow-up work at multiple locations, the sheriff's department says. An investigator is seen using a pole to search an underground tank behind Nancy Guthrie's home.

Savannah Guthrie posts another video on Instagram, saying her family is at an “hour of desperation” and they believe Nancy Guthrie is still out there. Savannah Guthrie asked for prayers and for people to report anything they might see or hear to law enforcement. No ransom note was mentioned.

A spokesperson for the FBI said the agency was not aware of ongoing communication between Nancy Guthrie's family and the suspected kidnappers, despite a deadline set for Monday evening.

The FBI says it managed to recover doorbell camera video of what it described as an armed person tampering with a camera at Guthrie's front door.

Video shows the person wearing a backpack and ski mask with holes for the eyes and mouth. The person tries to cover a camera near the front door with their gloved hand before ripping out a plant from the yard to block the camera's view.

Following the FBI's announcement, Savannah Guthrie posts images of the apparent kidnapper on Instagram. She writes: “We believe she is still alive. Bring her home,” and includes phone numbers for the FBI and county sheriff.

The White House says President Donald Trump watched the new surveillance footage and was in “pure disgust.”

Late Tuesday, the Pima County Sheriff's Department announced that a person who was detained during a traffic stop south of Tucson was being questioned in the investigation into Nancy Guthrie's disappearance. It was unclear if it was the same person who was captured on surveillance video outside her home.

Shortly after, the sheriff's department said it was conducting a court-authorized search of a location in Rio Rico, about an hour's drive south of Tucson, with the help of the FBI's Evidence Response Team.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)