Investigators nearing arrest of man who tampered with Nancy Guthrie's camera.

Investigators are focusing on a man seen tampering with Nancy Guthrie's doorbell camera the night she vanished, according to a former FBI agent.

Savannah Guthrie's 84-year-old mother was taken from her $1 million home in Tucson, Arizona, during the early hours of February 1.

Four months have passed without arrests or named suspects in the ongoing investigation.

Surveillance footage released earlier showed a masked individual armed at the entrance, adjusting a security camera before it was disconnected.

Former FBI agent Maureen O'Connell told The Megyn Kelly Show that authorities are closing in on this specific suspect.

"I think they're getting close to the porch guy, and when they get the porch guy, the floodgates shall swing open," O'Connell stated.

She estimates investigators are about 75 percent of the way to identifying and arresting the individual.

"The FBI recovered Nancy's doorbell camera footage days after she disappeared by accessing residual data stored on backend servers," reports indicate.

Pima County Sheriff Chris Nanos had initially stated no footage existed because the victim lacked a subscription to Google's video storage service.

Black-and-white video recovered shows a masked figure wearing gloves tampering with the device shortly before 1:47 am on February 1.

In her first interview, Savannah told Hoda Kotb that the footage is "absolutely terrifying."

"I can't imagine that is who she saw standing over her bed. I can't," Savannah said.

She described waking nightly in terror, imagining her mother's fear in the dark.

On Tuesday, Savannah appeared on The Today show, pleading for public help in finding her mother.

"I love you guys, and I love this place, and this is unusual and unprecedented to say the least," she told co-stars emotionally.

"I just want to take the opportunity to ask people to really to beg people to come forward - somebody knows something," she added.

The Guthrie family is offering a reward of up to $1 million for information leading to Nancy's safe return.

Earlier this week, a ransom note sent to the family claimed the senior citizen had died.

Two notes were sent to the family and local news outlets in the days following the January kidnapping.

The first note demanded millions of dollars in bitcoin for her release.

A second message indicated that Guthrie had died, sources told CBS. However, in a subsequent communication, the suspected kidnappers stated they never intended for her to die and issued an apology to her family.