tt_A former FBI agent has unveiled a disturbing new theory in the case, warning that a simmering “personal grievance” may be the dark motive behind the disappearance.

A former FBI agent believes that investigators should explore a new possible angle in the mysterious disappearance of Nancy Guthrie.

Jonny Grusing worked in the FBI’s Denver Division for 25 years, investigating violent crimes, missing persons, serial killers and more. He is also the author of “The Devil I Knew: Unmasking a Serial Killer,” about the true crime case of Scott Kimball.

Grusing made it clear that he is only operating off of information that has been made public in the case, and that he’s positing a new theory in case it might jog the memory of a member of the public who could help solve the case.

“The first thing he does is with his glove, and with his glove, it doesn’t look like he’s trying to take [the camera] off,” said Grusing of the suspect’s behavior on Guthrie’s stoop. “It looks like he’s trying to cover it with his right hand. “And then he looks down, he looks around, and he gets the branches, and he puts the branches up in front of it.”

Photos released on Feb. 10, 2025, show a “subject” on Nancy Guthrie’s property.  (Provided by FBI)

“Is there a chance, since we don’t have audio, that he is either knocking on the door loudly or that he has pressed the ring doorbell, [that] he’s trying to get Nancy to answer the door, and he’s shielding himself from being seen as a masked person, so she will, in her confusion, open the door?” Grusing asked rhetorically.

Grusing said that if that’s the case, the suspect likely wasn’t there to rob the home. Since Guthrie lives in a sprawling residential area, Grusing also believes it unlikely that the suspect was a robber who accidentally showed up at the wrong address.

Rather, he said, the suspect might have been there because he had a personal grievance against Guthrie, and might have lured her out of the home onto her porch.

Drops of blood appear to be on the front entrance to Nancy Guthrie’s home in Tucson, Arizona, Tuesday, February 3, 2026. Guthrie was last seen on Saturday night. (Derek Shook for Fox News Digital)

The possibility makes even more sense, Grusing said, when considering that blood was found spattered on Guthrie’s front porch and down the driveway, and authorities have not released any information about whether there was blood found inside the home.

The suspect also wore a gun in what is believed to be a cheap Walmart holster, and wore it on the front of his body, which Grusing described as not “tactically sound.” Grusing also believes that the gunman would have had trouble firing that gun with the gloves he was wearing, and that the gun may have just been a prop to instill fear in Guthrie.

“So, if the gun’s a prop, if he’s shielding himself from being seen, if he’s actually ringing the doorbell or knocking on the door, getting her to come, he wants to confront her about something in my opinion,” said Grusing.

An undated photo of Nancy Guthrie and Savannah Guthrie was provided by NBC in response to the disappearance of the 84-year-old mother of the “Today” show host. (Courtesy of NBC)

Grusing has always believed that in whatever interaction Guthrie had with the suspect, something went wrong, causing him to remove her from the house. Perhaps, he said, Guthrie identified him, causing a panic. He also says the kidnap-for-ransom theory doesn’t add up, given that alleged kidnappers never reached out to the Guthrie family directly.

Grusing wouldn’t speculate on what kind of grievance someone might have had with Guthrie, or why they might have had it.

But he wants the public to consider the possibility, just in case they remember someone saying they were wronged by a person fitting Guthrie’s description.

FBI agents canvass homes near Nancy Guthrie’s home in Tucson, Friday, Feb. 6, 2026. Guthrie was last seen on Saturday night as an investigation into her disappearance continues. (Kat Ramirez for Fox News Digital)

“It’s hard to be an expert in human behavior because it’s so unique to that person,” said Grusing, despite his quarter-century of experience.

“You know, I’m just trying to use the experiences of different cases and trying to apply any sort of logic to this in the hopes that someone from the public who has thought it might be someone they know whether it’s his family or whether now it’s a coworker or friend or associate or whatever, to put that one puzzle piece together that says, ‘Yes, and now I think it could be him.'”