Nancy Guthrie disappearance sparked harrowing 12-hour odyssey for Savannah

The ordeal began after what had been an ordinary evening with her children at "Today" co-host Carson Daly's home, she told Kotb last week.

"We had a beautiful, fun night together," she said, describing the visit.

On Sunday, her husband Mike Feldman returned from a golf outing.

"We were just saying hi, putting our stuff down, and the kids were running around - and my sister called me," she said.

Their mother, who has debilitating back pain and other mobility issues, was missing, she said.

It was around 2 p.m. in New York and noon back in Tucson. Savannah told her sister, Annie, to call 911. She already had.

Pima County deputies were at the home - where they found concerning evidence: blood on the front porch, the backdoors propped open, Nancy's valuables undisturbed but no sign of her whereabouts.

Annie and her husband, Tommaso "Tommy" Cioni, had already called local hospitals, hoping she'd been picked up by paramedics, to no avail. Savannah called them too.

Their brother Camron, who lives in Vermont, had also flown in. After arriving late at Annie's, Savannah remembers speaking with authorities again on the phone.

Off the bat, he had concerns, he said. He deployed search and rescue teams to scour the area - and also sent homicide detectives to the home.

"It's very concerning what we're learning from the house," he told reporters.

Nancy was taken in her pajamas, Savannah said. She had no shoes on. And the suspected abductor or abductors left behind valuables, like her purse, phone and Apple watch, as well as medication her life depended on.

"How is it possible that we are having to make a video speaking to a kidnapper who took an 84-year-old woman in the dead of night, in her pajamas, with no shoes, without her medicine and to beg for mercy?" Savannah asked Kotb.

"How can someone vanish without a trace? How? Someone knows something," Savannah said in her Dateline interview. "Even if that something's someone has been acting strange for the last 7, 8 weeks. Even if it's just that. Somebody knows."

The family has asked anyone with information to call 1-800-CALL-FBI.