In this photo taken May 31, 2014, agents in hazardous material suits are seen as the FBI searches a building in 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, June 2, shortly after announcing that they had found his car near Crissy Field, just south of the Golden Gate Bridge.

SAN FRANCISCO — Federal investigators said a search of a social media expert’s apartment in San Francisco turned up ball bearings, screws and components needed to make a homemade bomb designed to kill or maim, according to an affidavit.

Investigators said they found the materials inside a bag at the apartment of Ryan Kelly Chamberlain during a search over the weekend. The discovery prompted a manhunt for the 42-year-old Chamberlain that ended with his arrest Monday in San Francisco. The bag also contained a circuit board, screw top glass jar with batteries, a wire and a powdery green substance believed to be explosive material, FBI Special Agent Michael Eldridge said in the document.

“FBI bomb technicians believe that the circuit board described above was designed to serve as a remote control, allowing detonation of the device from afar,” Eldridge said. “They further believe that the device was designed to maim or kill a human being or human beings.”

The FBI has not said what, if any, plans Chamberlain might have had for the device, or how they were alerted to the material. Though Chamberlain was considered armed and dangerous, FBI spokesman Peter Lee reiterated Tuesday that he did not seem to pose an immediate threat to public safety.

Chamberlain appeared in federal court Tuesday after being charged with one count of possession of an illegal destructive device. He was accompanied by a public defender and did not enter a plea. He had on the same shorts and sweatshirt when police arrested him near the Golden Gate Bridge.

On Saturday, as authorities arrived to search the apartment, they spotted Chamberlain and a woman leave and drive away.

Chamberlain returned on foot about 30 minutes later, when Eldridge said he identified himself and asked if they could talk in a nearby coffee shop. After a short discussion, Chamberlain asked if he could leave, and Eldridge said he could, the document states.

Authorities tried to follow him as he drove off but decided to pull back when he began speeding and running lights, Eldridge said. Authorities then searched the apartment and found the bomb materials.

Chamberlain was arrested by police officers who responded to a report that a person matching Chamberlain’s description had been spotted, Police Chief Greg Suhr said.