Police have released a 10-page file revealing an action taken by Nancy Guthrie before she was kidnapped, raising serious concerns about whether she is still alive

Investigators are still searching for “Today” host Savannah Guthrie’s 84-year-old mom, who has been missing since Sat. Jan. 31

Pima County Sheriff Chris Nanos; Nancy Guthrie and Savannah Guthrie.Credit : NBC; Savannah Guthrie/Instagram

Speculation about exactly what Nancy Guthrie did after she returned home on the night she vanished has mounted since the 84-year-old was reported missing over the weekend.

On Sat. Jan. 31 at 9:48 p.m., the 84-year-old mother of Today show host Savannah Guthrie, 54, returned to her Tucson, Ariz., home after having dinner with her daughter Annie and her husband at their house, Pima County Sheriff Chris Nanos said at a press conference on Thursday, Feb. 5.

Her family dropped her off and that was apparently the last time anyone saw Nancy.

“At 9:50 p.m. that garage door closes, because [at] that time we assume that Nancy’s home and probably going to bed,” Nanos said at the press conference.

On Friday, Feb. 6, Nanos cleared up the confusion when he told PEOPLE, “We know she had gone to bed.”

Savannah Guthrie and mother, Nancy Guthrie.Savannah Guthrie/Instagram

In a previous interview with NBC News, Nanos said, “When you’re taken from your bed and you don’t want to go somewhere, that’s an abduction.”

But Nanos “meant that figuratively and did not mean she was literally taken from her bed,” the sheriff’s department later clarified to NBC.

After Nancy went to bed, however, authorities aren’t exactly sure what she did, Nanos told PEOPLE.

“Did she get up and answer the door?” he says. “Did she get up to go to the bathroom? Did she go to get something out of the refrigerator?

“I just know that this 84-year-old mom, grandma, went to bed that night and in the morning she was missing,” he says.

Missing-person poster for Nancy Guthrie.Pima County Sheriff’s Department

From what authorities have said, there was no activity at the house until 1:47 a.m., when Nancy’s doorbell camera disconnected, he said at the press conference.

At 2:12 a.m., the software from the doorbell camera detected someone, but no video is available because there was no subscription, so investigators cannot tell who or what that was at this point. “We just have no video, but we’re not giving up on that,” Nanos said at the press conference.

At 2:28 a.m., Nancy’s pacemaker app indicated a disconnection from her phone. Nearly 40 minutes passed between the time the doorbell camera detected a person and the time Nancy’s pacemaker app indicated a disconnect.

Nanos has said previously that he believes Nancy is alive.

Authorities, though, say they have no suspects at the moment.

They are looking into alleged ransom notes that were sent to various news outlets.

During the Feb. 5 press conference, FBI Phoenix Special Agent in Charge Heith Janke said one individual has been arrested for making a phony ransom demand.

Savannah and her siblings addressed their mother’s possible abductors in a tearful plea video posted to Instagram on Wednesday, Feb. 4.

The notes included a dollar amount and two deadlines — the first at 5 p.m. on Thursday, Feb. 5 and a second for Monday, Feb. 9, if the initial demand was not met. He added that one note referenced an Apple Watch and another mentioned a floodlight, but provided “no proof of life.”

Anyone with tips or leads is asked to call 1-800-CALL-FBI in addition to the Pima County Sheriff’s Department number, 520-351-4900.