Nancy Guthrie live updates: Suspect's clothing may have been purchased at Walmart; family cleared

The FBI agents are conducting an "extensive search" on Wednesday along multiple roads in the Catalina Foothills neighborhood surrounding Nancy Guthrie's Tucson-area home, the bureau's Phoenix office said.

"We are asking the media and motorists to follow all traffic laws and to remain especially cautious when passing law enforcement near roadways," FBI Phoenix said in a statement.

The FBI said it continues to offer a $50,000 reward for information leading to the recovery of Nancy Guthrie.

A delivery driver who said he was detained by investigators in the Nancy Guthrie disappearance claimed in an interview that law enforcement officers had been following him.

The man, who only wanted to be identified as Carlos, said he was driving his Nissan Rogue on Tuesday evening in Rio Rico, Arizona, about 50 miles south of Tucson, when he noticed he was being trailed by a law enforcement vehicle.

"They were following me," Carlos told ABC Phoenix affiliate station KNXV. "And once I saw they were following me, I pulled over. They didn't even have to [make] a traffic stop. I got out of the car and they arrested me as soon as I got out of the car."

Carlos said he was not immediately told why he was being detained. But when an FBI agent and a Santa Cruz County deputy sheriff arrived at the scene, "They told me I was being detained for kidnapping."

"And I asked them, kidnapping of who?" said Carlos, adding that he was told of Nancy Guthrie.

He said that after being detained for several hours and having his vehicle thoroughly searched, he was released.

"Deputies detained a subject during a traffic stop south of Tucson," the Pima County Sheriff's Office said in a statement, confirming the man was "questioned in connection to the Nancy Guthrie investigation."

A woman who described herself as Carlos' mother-in-law told KNXV that investigators, armed with a search warrant, swarmed her home on Tuesday night, claiming they got a tip that Nancy Guthrie, the mother of "Today" show host Savannah Guthrie, was inside her house.

"I told them, 'You can go in and search my house,'" the woman said. "There's nobody there."

Investigators spent hours conducting a court-authorized search at a location they said was connected to the individual who was detained for a few hours for questioning during a traffic stop Tuesday.

A woman told reporters that her daughter's husband, who works as a delivery driver in Tucson, was a target of Tuesday's search in Rio Rico. Investigators converged on her residence.

"They're going in and out of my house taking a lot of pictures and everything," the woman told reporters. "Like I told them, we're not hiding anything."

She said authorities searched her home after they received a tip related to the Nancy Guthrie investigation.

The man was later released.

The Pima County Sheriff's Department, with assistance from the FBI, detained and released an individual after questioning them in connection with the abduction of Nancy Guthrie, a law enforcement official briefed on the investigation told ABC News.

The individual was detained in a location south of Tucson, the source said, and law enforcement searched a location associated with the individual.

In a statement on social media, the Pima County Sheriff's Department said deputies "detained a subject during a traffic stop."

A court-authorized search was carried out by the sheriff's department, with assistance of the FBI's Evidence Response Team, at a location in Rio Rico, Arizona, about 60 miles south of Tucson, related to the investigation, the department said. The operation was expected to last several hours, according to the department.