A former FBI agent has challenged a key theory in the disappearance of Nancy Guthrie.

The 84-year-old mom of Savannah Guthrie has been missing for more than a month. Guthrie vanished from her home near Tucson in the early hours of February 1. Investigators say there were signs of a struggle at the property, including blood on the porch that was later confirmed to be hers. Doorbell footage also showed a masked individual approaching the house and tampering with the camera before it was disabled.

Now, a possible clue in the case has turned out to be a dead end, according to latest reports. Gloves discovered near the home were initially thought to belong to the suspect seen in the footage, but DNA testing later showed they belonged to a nearby restaurant worker who had no connection to the disappearance. It comes after a mystery man who claimed he “saw Nancy 5 days ago” offered chilling new proof.

Former FBI agent Greg Rogers has dismissed the idea that the incident was a robbery gone wrong. Speaking in an interview, he says that the suspect’s actions – such as disabling the camera and moving cautiously around the property – suggest the crime was planned.

“I have never thought this was a robbery gone wrong,” Rogers told Parade.

“There were too many opportunities to have hit the house when nobody was home. There are a good number of interstate home burglars that are much more careful, case homes, know when the owners are away, and are in and out in minutes. They do not hit residences when it is almost guaranteed someone is home.”

Greg Rogers said there is no evidence that valuables were taken from the home of missing Nancy Guthrie, casting doubt on the theory of a botched robbery. He believes the circumstances suggest the person behind her disappearance may have known her.

“I think it is highly likely that someone who knew Guthrie and/or had something to do with her—[think] home maintenance, health care, yard and pool care—was involved,” Rogers said.

“One of those persons could have been hired to give info about security systems, Guthrie’s schedule etc. That person could have also worked in one of those positions to be able to learn that same information.”

Authorities believe Nancy Guthrie may have been abducted from her Arizona home in the middle of the night. They released Google Nest camera footage showing an armed, masked person standing on her front stoop shortly before she disappeared, but no suspect has been identified.

Experts reviewing the footage believe the individual may have used a walkie-talkie instead of a mobile phone to avoid leaving digital traces. Guthrie’s family is now offering a $1 million reward for information that could help bring her home safely.

Pima County sheriff stonewalled US Navy after it offered to help in Nancy Guthrie case? New details emerge

The United Cajun Navy said it sent Pima County Sheriff Chris Nanos a 41-page plan offering assistance in the search for Nancy Guthrie.

Sgt. Aaron Cross, president of the Pima County Deputies Organization, said that he hopes Nanos will accept the help. “More bodies are always better than less,” Cross said.

Amid the search for Nancy, four detectives and a sergeant from the Pima County Sheriff’s Office have been assigned to a joint task force with the FBI, operating out of the bureau’s Tucson field office.

Read More | Savannah Guthrie’s husband Michael Feldman lands in Tucson amid search for Nancy, sparks anger: ‘Where has he been?’

“Everybody wishes that we had some hot leads, that the whole department’s working, trying to run down to solve this quickly. So the fact that we’re reducing the amount of manpower working it, I mean, it’s hard to say what kind of sign that signals,” Cross said.

Cross previously acknowledged that there was some friction between local police and the FBI.

“I know (there were) issues between the sheriff and the FBI early on, but now that they’re working on one task force, is that positive? I hope so. I hope it’s a more collaborative effort with the federal agency,” he said.

“There was some talk and discussion that it was police officers out in the field just discarding [the gloves], that is so far from the truth,” Nanos said.

“We knew that at that time, we believed wholeheartedly that those gloves belonged to a restaurant and guess what? The owner of the glove, we found working at a restaurant across the street. It has nothing to do with the case,” he added.

However, Nanos also explained that other gloves found near the home could have a different DNA match.

“It’s a challenge because we know we have DNA, but now we have to deal with that mixture and how we’re going to separate it,” Nanos said.

The sheriff recently said that authorities are “definitely closer” to tracking down the suspect or suspects in the case.

“I think the investigators are definitely closer,” Nanos said in an NBC interview. “We got a lot of intel, a lot of leads, but now it’s time to just go to work.