What we know about the abduction of Savannah Guthrie's mother

The mystery surrounding the disappearance of the 84-year-old mother of NBC News anchor Savannah Guthrie has deepened.

Nancy Guthrie disappeared in the middle of night from her home in Tucson, Arizona, on 31 January and authorities believe she was taken against her will.

Police in Arizona have not yet identified a person of interest in the suspected abduction and continue to investigate a series of apparent ransom notes that may have been sent from the person or people behind the alleged crime.

The Guthrie family has made several public pleas for her safe return, and has asked for proof that their mother is still alive.

Here is what we know about the case.

When did Nancy Guthrie go missing?

Guthrie was last seen at her home in Catalina Foothills, an affluent neighbourhood roughly six miles (10km) north-east of Tucson, on 31 January evening, when family members dropped her off around 21:30 local time (04:30 GMT).

At 01:47 local time on 1 February, a doorbell camera to her home was disconnected and removed.

At 02:28, the app on her pacemaker, an implanted cardiac device, disconnected from her phone.

Concern grew when members of her church noticed her absence at Sunday's service and notified her family.

After the family called 911, authorities began a search that soon included volunteers and federal officers from Border Patrol, which stretched into the next morning.

More than a week later, officials released videos and images showing a masked person, who they say was armed, at her doorstep the night she disappeared.

The footage showed the person approach the front door of her home, then check the camera before moving away, picking up some vegetation from the ground and using it to cover the camera lens.

Savannah Guthrie shared the video on Instagram. "Someone out there recognises this person," she said "We believe she is still out there. Bring her home."

Police have said they found blood on Nancy Guthrie's porch and analysis confirmed it was hers.

Officials have also warned that she may be in dire health without her medication.

She has been described as "not in good physical health", but has no reported cognitive issues, Pima County Sheriff Chris Nanos said.

As media crews have descended on the quiet Arizona suburb where the missing woman lives, authorities closed access to her street, nestled below the Santa Catalina mountains on roads lined with the state's Saguaro cactus.

What did the alleged ransom notes say?

FBI Special Agent Heith Janke said his agency had been reviewing a possible ransom note sent to several media outlets.

Details about an Apple watch and a floodlight at Nancy Guthrie's home were in the note.

Police said one ransom note sent to the media had two deadlines: one at 17:00 on 5 February and another on 9 February.

The FBI also said it had arrested a person for a fake ransom note on 5 February.

Then on 6 February, authorities said they were investigating a new message related to the case. A statement from the FBI and the sheriff's office said they were "inspecting the information provided in the message for its accuracy".

The statement did not say who received the note, or any details that it may have contained.

A presenter for a local affiliate of CBS News told the BBC that her channel received the "message". The presenter did not detail what was in the message.

In her emotional plea, Savannah Guthrie said she and her family were aware of the ransom note as well. She addressed the potential abductor or abductors directly.

"We are ready to talk," she said, adding that, "we need to know without a doubt that she is alive and you have her... Please, reach out to us."

In a separate video on 5 February, her brother Camron said the family still had not received any contact from "whoever is out there holding our mother", adding: "We want to hear from you".

On 6 February, the family released a third video, with Savannah Guthrie saying: "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 added: "And we will pay."

On Monday, ahead of a reported ransom deadline, Savannah Guthrie released another video pleading for the public to help locate her missing mother.

"I just want to share a few thoughts as we enter another week of this nightmare," she said in a the video posted on Instagram. "She was taken, and we don't know where. And we need your help."

On 6 February, officials said they are offering a reward of $50,000 (£36,000) for information that leads to an arrest.

US President Donald Trump, who ordered federal authorities help in the investigation, has called the case "very unusual".

Guthrie, 54, is an American broadcast journalist who has served as the co-anchor of NBC News' Today since 2012. She is also the network's chief legal correspondent and a primary anchor for its election coverage. Previously, she was NBC News' White House correspondent.

Guthrie was born in Australia, but when she was a toddler her family moved to Tucson, Arizona, where she grew up for most of her childhood. She did not travel back to Australia until 2015, visiting with her mum Nancy and fulfilling her "lifelong dream to return", she told the Daily Telegraph.

"For my mum to come back and get to see where she used to live brings back a lot of happy memories with my dad," Guthrie told the Daily Telegraph.

Guthrie, who maintains a public stance of political neutrality, has interviewed presidents Barack Obama, Joe Biden and Trump.

She has a law degree from Georgetown University and a bachelor's degree in journalism from the University of Arizona.

She has won an Edward R Murrow Award for ethical electronic journalism and multiple News Emmys, including for an interview with Trump a month before the 2020 election.