Ryan Kelly Chamberlain II should be considered armed and dangerous, an FBI spokesman said during a weekend news conference. Peter Lee said a search Saturday of Chamberlain's apartment in the Nob Hill neighborhood turned up explosive material.
Chamberlain, 42, is a native of the San Francisco area, the San Francisco Chronicle said. He has been involved in political consulting, and worked as an independent contractor for the Chronicle during the 2012 football season.
Randy Bramblett, 32, a professional cyclist and personal trainer in San Francisco, told the Chronicle he got to know Chamberlain when he was working for Project Sport. Bramblett said Chamberlain "got weird" after the sports marketing company dismissed him.
"The thing is, there was a lot of strange behavior since November," Bramblett said. "He stopped answering his phone. I think he became an extreme introvert."
Chamberlain ran for the Republican Party's county committee in San Francisco 12 years ago. He uses the Twitter handle @poliholic.