Morning TV star Savannah Guthrie fought back tears in a gut-wrenching video alongside her two siblings as the trio desperately appealed to their missing mother Nancy's captors and begged for proof she is alive. 

Nancy, 84, vanished on Saturday evening after she was dropped off at her sprawling Arizona property by her Italian son-in-law Tommaso Cioni - the last person to have seen her.

The Today Show anchor described her mother in glowing terms in the new clip shared on Instagram with her 1.3million followers as she pleaded for Nancy's safe return Wednesday night.

'Our mom is a kind, faithful, loyal, fiercely loving woman of goodness and light. She's funny, spunky and clever. She has grandchildren that adore her and crowd around her and cover her with kisses,' Guthrie said.  

Guthrie graciously thanked everyone across the country who offered prayers and support before detailing her 'beloved mom' Nancy's fragile state prior to her disappearance.

'She is 84 years old. Her health, her heart is fragile. She lives in constant pain. She is without medicine, she needs it to survive. She needs it not to suffer,' the mom of two added.

Guthrie - surrounded closely by her sister Annie and brother Camron - then directly addressed her mother's possible captors, in the first public admission that she may be held for ransom.  

'We too have heard the reports about a ransom letter in the media. As a family, we are doing everything that we can,' Guthrie said in the clip. 

Guthrie then said to the potential kidnappers that 'we are ready to talk' but wanted proof that they weren't potentially using fraudulent images of her. 

'We live in a world where voices and images are easily manipulated. We need to know, without a doubt, that she is alive and that you have her. We want to hear from you and we are ready to listen. Please, reach out to us,' she said through the tears.

Guthrie then directly addressed her mother.

'Mommy, if you are hearing this, you are a strong woman. You are God's precious daughter, Nancy,' she said.

'We believe and know that even in this valley, he is with you. Everyone is looking for you, mommy, everywhere. We will not rest, your children will not rest until we are together again.'

'We speak to you every moment and we pray without ceasing and we rejoice in advance for the day that we hold you in our arms again. We love you, mom,' the NBC star added.

Annie and Camron Guthrie then echo their sister's words: 'We love you, mom. Stay strong.' 

The video was simply captioned: 'Bring her home.' 

Just minutes after the video hit the platform, President Trump confirmed via a Truth Social post that he spoke with Guthrie and had heard her pleas.

'I spoke with Savannah Guthrie, and let her know that I am directing ALL Federal Law Enforcement to be at the family's, and Local Law Enforcement's, complete disposal, IMMEDIATELY,' the commander in chief wrote on his platform. 'We are deploying all resources to get her mother home safely. The prayers of our Nation are with her and her family. GOD BLESS AND PROTECT NANCY!' 

Retired FBI agent Dan Brunner told the Daily Mail he believes that the message was released in coordination with the bureau. 

'I absolutely believe this is coordinated with the FBI and members of the behavioral analysis unit,' he said. 

'They use a lot of keywords to personalize her to make her human how they meant to her, calling her mommy numerous times a lot of keywords that hopefully the kidnappers would be able to feel some empathy for who they've done this to.' 

CNN legal analyst Andrew McCabe said in response to the video that it appeared unclear whether the Guthries had a legitimate offer.

'I feel like this is a fairly strong signal that they do NOT believe that they've had a legitimate ransom demand yet... This, to me, reads like an effort to establish a line of communication,' he said. 

Cops said on Tuesday that they had turned the $1million adobe-style house back over to the Guthrie family, however the FBI had returned to the property by Wednesday.

Police have previously been investigating the possibility that a ransom demand has been made. 

The FBI descended on the Tucson home on Wednesday as law enforcement efforts were stepped up dramatically in the search for the missing retiree.

A pickup truck from the Pima County Sherriff's Department arrived at Nancy's home, along with two carloads of FBI investigators. The house has since been taped off, and agents were still inside as of 5.30pm local time.

K-9 units were also spotted combing the inside, according to Fox News.

Meanwhile, a second pair of investigators were at the home of Savannah Guthrie's sister Annie. The detectives were seen collecting what looked like a tripod and lights from their car before going back inside.

Officers were previously spotted at the house, where the Today Show anchor is believed to be holed up, on Tuesday. 

Wednesday's visit came shortly after a detective from an online pedophile unit showed up to talk to the Guthrie family.

Seen outside the house in Daily Mail photos, the man was wearing a t-shirt emblazoned with the Internet Crimes Against Children Task Force badge.

The FBI affiliate specializes in combating online grooming and technology enabled child abuse. 

The uptick in activity comes shortly after a source told a local ABC News affiliate that the FBI is rushing in outside experts - including hostage negotiation specialists.

Until Tuesday, the case had been handled entirely by the Pima County Sheriff's Department who called in extra help after realizing the devout grandmother had been abducted.

Signs of a struggle can still be seen at her home, with her Ring doorbell removed and a splatter of blood by the entrance door.

Nancy lives alone at the house in the affluent Catalina Foothills neighborhood, where authorities found her phone, wallet and car following her mysterious disappearance on January 31.

An Apple Watch was also found inside the property, which investigators say stopped syncing with her pacemaker at around 2am - suggesting she was taken from her home at around that time.

Officers are now looking into Savannah's superfans who have piled her with gifts and mail before her mother was abducted, the Daily Mail revealed earlier on Wednesday.

Investigators specifically asked NBC whether there were any troubling fan interactions that could be relevant to the case, a senior source claimed.

No suspect has been identified and police insist there is no danger to the wider public. 

However, investigators have not ruled out that Nancy may have been targeted because she is the mother of the famous Today show host.

At the same time, though, the Pima County Sheriff's Department is looking into the possibility that Nancy's kidnapping may be linked to a trespassing case in January, TMZ reports.  

In that case, one of her neighbors told authorities he noticed a suspicious person outside of his own home. 

But when the unidentified lurker triggered a motion sensor, causing floodlights to switch on, he fled the scene and witnesses were unable to provide a description of the suspect.

Police are now going door-to-door collecting security camera footage from neighbors as they attempt to identify a suspect and are searching for a vehicle of interest, a law enforcement source said.

They are also investigating the possibility that a ransom demand has been made.

Despite the lack of answers, Pima County Sheriff Chris Nanos has faith that Nancy is still alive.

'We have nothing else to go on but the belief that she is here,' he said in an interview with NBC's Liz Kreutz. 'She's present. She's alive, and we want to save her.' 

He noted that his department is taking all tips and leads very seriously.

'The leads we've got coming in are critical to us. They're valuable, and we're sharing those with the FBI and others,' Nanos said.

To aid in the investigation, President Trump announced he was allocating additional federal support for the search.

He said on Tuesday he planned to call Savannah, noting that his thoughts were with the news anchor amid the 'terrible' situation.

'I'm going to call her later on, I think it's a terrible thing,' Trump said. 'Very unusual situation, but we're going to find out.'

Then, on Wednesday, the president made good on his promise, NBC News anchor Tom Llamas reported on air.

He said that Trump took the moment to 'offer words of support for her and her family as they search for her mother'.

Authorities are expected to provide another update into the investigation Thursday. 

Nancy's upscale Arizona neighborhood is quiet and mostly dark at night, lit mainly by car headlights and homes spaced far apart. 

Long driveways, front gates and desert plants provide a buffer from the winding streets and curious eyes.

Saguaro cacti tower sits above the roofline of Nancy's Tucson-area home, and wispy trees partially block the view of the front door.

Those are the conditions that investigators are faced with as they try to piece together the moments before and immediately after Nancy's disappearance. Authorities offered no detailed update Wednesday.

'Is there somebody out there who's kidnapping elderly people in the middle of the night, every night?' Pima County Sheriff Chris Nanos said Tuesday. 

'We don´t believe that's the case. We believe Nancy was taken from her home against her will.'

The sheriff suggested there was video from some cameras, though he didn´t elaborate, adding: 'That's all been submitted and we're doing our best with the companies that own those cameras or built those cameras.'

Nanos' office said Wednesday that detectives still were speaking with anyone who had contact with Nancy last weekend but that no suspect or person of interest had been identified.