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A San Francisco man wanted by the FBI for possession of explosive materials and arrested after a three-day manhunt appeared in court Tuesday where he faces charges of possession of bomb-making material.

Ryan Kelly Chamberlain II, 42, was captured by federal agents and San Francisco police officers shortly after authorities said they had found the suspect's car near Crissy Field, located south of the Golden Gate Bridge.

According to the affidavit Chamberlain's apartment contained "an illegal destructive device" and supplies that could be used in an Improvised Explosive Device. These items included a screw glass jar containing batteries and a powdery substance and an assortment of ball bearings and screws believed to be intended projectiles, the affidavit said.

A law enforcement official told the Associated Press that Chamberlain was arrested without incident. Morgan Manos, an Uber car driver who witnessed the arrest and captured it on video, told the San Francisco Chronicle that Chamberlain "looked pretty surprised and frantic." Chamberlain was wearing shorts, a sweatshirt and a beanie hat, Manos said, adding: "They took him down hard."

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.

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"Anyone who has the means, methods and access to make a bomb should be considered armed and dangerous," Lee said before the arrest.

On Monday, KTVU reported that Chamberlain wrote a three-page note that was released to his friends on social media. The note reportedly described Chamberlain's depression, the breakdown of his personal relationships, and his search for a purpose in life.

"When 2013 came, it did me in," Chamberlain's note read. "I've been fighting and fighting to get out of it. But it wrecked me. And it led to what happened today (Saturday's raid). In the span of a few months, everything that mattered to me betrayed me.

"I explored myriad ways I could put an end to what I was going through," Chamberlain's note continued. "I binged-watched dark TV, sometimes didn't get off the couch for days, and scoured the Internet absorbing fuel for morbid fantasies. Some of that activity seemed to attract the attention of some visitors [Saturday] ... who have made it rather evident that this is the end of the line for me."

Later Monday, Chamberlain wrote an addendum to his note that read: "A panicked update to my letter that should have posted by now. Nothing they're reporting is true. No 'stashes.' Not 'armed and dangerous.' No car 'rigged to explode.' I explored some ugly websites, a year-ish ago. I was depressed. I let Walter White get to me. I thought I was done. That's it. No one was ever in danger. And recently I was all better. I owe my friends and my girlfriend for that. But I guess I did enough for the damage to be done. I'm so sorry everyone."

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.

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

"He's a nice guy," Wentz told The Associated Press.

Wentz said it didn't seem like Chamberlain was staying in the apartment on Jackson Street. She said when she mailed him his paycheck in April, he told her he would have to go the apartment to pick it up. She said he seemed 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? I tried to ask him about the situation but he was kind of evading my question," Wentz said.

Randy Bramblett, a personal trainer and professional athlete in San Francisco, said he became friends with Chamberlain through Project Sport, a local 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.

He 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.

Click for more from KTVU.

The Associated Press contributed to this report.