SAN FRANCISCO » A San Francisco social media maven and former political consultant who was wanted on suspicion of possessing explosives has been taken into custody after a three-day manhunt.

Federal agents and the San Francisco police said they captured Ryan Kelly Chamberlain II, 42, on Monday afternoon shortly after announcing that they had found his car near Crissy Field, just south of the Golden Gate Bridge.

Though Chamberlain was considered armed and dangerous, FBI spokesman Peter Lee said Monday that he did not seem to pose an immediate threat to public safety.

"Anyone who has the means, methods and access to make a bomb should be considered armed and dangerous," Lee said before the arrest. "That is the reason why we want to bring him in safely soon."

Multiple agencies, including hazardous materials crews, searched Chamberlain’s apartment Saturday in San Francisco’s Russian Hill neighborhood, blocking off the street to vehicle and pedestrian traffic for much of the day.

Lee gave no further details about the nature of the investigation, and the affidavit and search warrant used to enter Chamberlain’s home remained under seal.

Brooke Wentz, his boss at a music rights consultancy group, said Chamberlain last contacted her Friday to remind her to deposit his paycheck in a new bank account. The conversation was uneventful and Wentz said she was "tremendously dumbfounded" by the news that the contractor she had hired to handle her company’s social media accounts was wanted by the FBI.

"He’s a nice guy," Wentz said.

She said it didn’t seem like Chamberlain was staying in his apartment. When she mailed him his paycheck in April, he told her he would have to go to the apartment to pick it up.

She said he seemed to be under financial pressure because he told her that two friends who were leasing his apartment left without telling him and he had to scramble to pay for two rentals.

"I wondered what kind of friends would do something like that," Wentz said. "I tried to ask him about the situation, but he was kind of evading my question."

Randy Bramblett, a personal trainer, said he became friends with Chamberlain through Project Sport, a sports marketing company. The company let Chamberlain go when it was sold in November, and he soon lost touch with friends and stopped returning calls and messages, Bramblett said.

"We all knew that he was a very emotional guy and when he didn’t get his own way he would say, ‘Screw you, I’m going to go do my own thing,’" Bramblett said. "I’ve never seen him be violent, ever, but I would definitely say that maybe emotionally and mentally he was a little unstable."

Chamberlain had worked for years as a political consultant on Democratic campaigns, Bramblett said.

Alex Clemens, a partner of the San Francisco-based Barbary Coast Consulting, said Chamberlain is well known in the city’s political circles and had been a fixture on the campaign trails for more than a decade. His work in the field ended several years ago.

Clemens, who briefly hired Chamberlain for a project in 2009, said people who know Chamberlain are stunned.

"I believe there’s been a failure in his support system. I’m sad for that," Clemens said. "I hope he will reach out to those who will help him."

Chamberlain also worked as an independent contractor for The San Francisco Chronicle during the 2012 NFL season, doing social media to boost coverage for the San Francisco 49ers Insider iPad app, the newspaper said.

Chamberlain also taught a "Grass Roots Mobilization" course to graduate students in the public affairs program in 2011, said Anne-Marie Devine, a spokeswoman for the University of San Francisco. Chamberlain taught for one semester and wasn’t invited to teach another course, she said.

She said she didn’t know why he was let go because hundreds of adjunct professors come and go at the university.

Associated Press writer Channing Joseph in San Francisco contributed to this report.