More than 100 days after the mother of Savannah Guthrie vanished from her Arizona home in a chilling kidnapping case that gripped the nation, the sheriff leading the investigation revealed he is no longer personally in contact with the Guthrie family.

Chris Nanos made the striking admission as mounting frustration surrounds the stalled search for 84-year-old Nancy Guthrie, who disappeared from her Tucson home in the early hours of February 1.

'I personally am not,' Nanos told People when asked whether he still communicates directly with the family, saying contact is now handled by detectives and the FBI.

'If they need the family for anything, they get in touch with them and the family,' Nanos said. 'It works both ways.' 

The revelation came as investigators remain without a suspect or arrest in the high-profile case despite months of FBI-backed investigative work, surveillance footage of a masked man outside Nancy's home, and a $1 million reward offered by Savannah and her siblings for information leading to Nancy's recovery.

Nanos' admission has stunned observers because he had previously spoken publicly about communicating with Savannah in the days immediately following her mother's disappearance.

Just six days after Nancy vanished, Nanos revealed how he and the NBC host had been texting and occasionally speaking by phone.

'We text or, every now and then a phone call,' the sheriff said at the time. 'But no, I've not even sat down with her face-to-face. She's got a lot on her plate.'

'The FBI and my detectives and those, they've been talking with her face-to-face. She doesn't need to talk to me,' he said.

Now, with the investigation stretching beyond the grim 100-day mark and few public breakthroughs emerging, the relationship between the sheriff and the family has become another flashpoint in a case increasingly clouded by public frustration.

The lack of visible progress has reportedly left those close to the family increasingly distressed as life slowly resumes around them while the case remains unsolved.

Nanos insists investigators are continuing to work aggressively behind the scenes and says key details are intentionally being hidden from the public.

In an earlier interview with KOLD, the sheriff revealed investigators possess information they are deliberately withholding.

'It's not done because we got to keep it secret,' Nanos explained. 'It's done because we got to protect our case.'

Nanos also maintained that he remains convinced detectives will eventually identify the masked suspect seen on surveillance footage tampering with Nancy's doorbell camera.

'I believe at some point in time, we will make an arrest in this case,' he said. 'And whoever that individual is, that individual will have a right to a fair and impartial trial.' 

The sheriff has repeatedly argued that the public is underestimating the complexity of the investigation, pointing to mountains of digital and forensic evidence still being analyzed.

Authorities have reportedly combed through 'thousands and thousands' of hours of video footage gathered from traffic intersections and Ring doorbell cameras across the Tucson area.

Meanwhile, DNA evidence recovered near the scene has undergone extensive testing at an FBI crime lab after initially being processed by a private laboratory in Florida.

'That testing moves at a snail's pace,' Nanos acknowledged. 'There's way too much work to be done, that is ongoing, with some of the physical evidence we have,' he told People. 'And we're not going to give up on it just because it's been 100 days.'

The sheriff added: 'When you have the best minds of the country working on problems, I think they're gonna solve them. It just takes time.'

Savannah, meanwhile, has returned to co-hosting duties on Today while continuing to plead publicly for information about her mother's whereabouts.

Earlier this month, the longtime television anchor posted an emotional Mother's Day tribute on Instagram begging for help.

'Mother, daughter, sister, Nonie - we miss you with every breath,' Savannah wrote.

'We will never stop looking for you. We will never be at peace until we find you.'

She continued: 'We need help. Someone knows something that can make the difference. Call 1800CALLFBI. You can be anonymous and the reward remains available. Please keep praying. Bring her home.'

Nancy Guthrie was last seen on January 31 after spending the evening with her daughter Annie and son-in-law Tommaso Cioni before being dropped off at her $1million home in Tucson's affluent Catalina Foothills neighborhood.

Hours later, investigators believe she was abducted.

Her doorbell camera was disconnected, but federal investigators later managed to recover haunting surveillance footage showing a masked man carrying a backpack on her doorstep in the early hours of February 1.

Authorities also revealed ransom letters tied to the case had been mailed to TMZ and local media outlets, further deepening the mystery surrounding the grandmother's disappearance.

Despite an enormous investigation involving the FBI and local law enforcement, the case appears to have slowed dramatically in recent months.

According to reports from Page Six, investigators have uncovered only limited physical evidence, including a single strand of hair and a glove found near Nancy's home.

No suspects have been publicly identified.