Authorities said Peter Francis Stager was seen in videos of the riot holding an American flag on a pole, then using that pole as a weapon to strike the officer who was working to secure the building.
In the call with police chiefs, Christopher Wray, the FBI director, and Kenneth Cuccinelli, the acting deputy secretary of the Department of Homeland Security, warned about potential attacks on state capitols, federal buildings, the homes of congressional members and businesses, according to one of the chiefs on the call.
The projectile he is accused of throwing was not the one that killed Police Officer Brian Sicknick, who was also struck in the head by a fire extinguisher during the melee and later died from his injuries, authorities said.
An image released by the FBI shows a man in a plaid jacket with a blue knit cap wielding a fire extinguisher during the incident where the officer was reportedly dragged into the crowd. There are reports that the officer died shortly after being hit with a fire extinguisher.
Responding officers evacuated the residential buildings in the area after hearing the warning. They were working to get people out when the explosion detonated.
They identified the dead man as James David Hawley, 47, of Cleveland, accused of killing Norma Matko, 69, in Belmont County, Ohio, and kidnapping her daughter, Thoue Nichole Bronowski, 45, who is his ex-girlfriend.
Despite evasive efforts, the drone struck the helicopter, forcing the pilot to initiate an emergency landing. The drone damaged the helicopter's nose, antenna and bottom cowlings, according to court papers.
Religious groups have been increasingly targeted, as officials saw a nearly 14 percent increase in attacks against Jews and Jewish institutions, the report found.
The two men were driving a silver Hummer truck from Virginia. Police said they found the car parked and unoccupied around 10:20 p.m.; about seven minutes later, two police officers on bicycles saw two men in possession of firearms.
The FBI started monitoring the group in March when an informer stepped forward to warn of danger against law enforcement. The informant told the feds that the group was trying to obtain home addresses of law enforcement officers.