"I think the scope and scale of this investigation and these cases are really unprecedented, not only in FBI history, but probably DOJ history," Acting U.S. Attorney Michael Sherwin said in a press briefing on Tuesday (local time).
"The Capitol grounds outside and inside are... a crime scene."
Sherwin said 70 criminal cases had been filed to date.
While many of them involved people whose photos went viral on social media, such as one of a man pictured sitting at the desk of a staffer of House Speaker Nancy Pelosi, he said more serious charges were coming and a grand jury had been reviewing the cases.
"We're looking at significant felony cases tied to sedition and conspiracy," Sherwin said, noting his office has launched a strike force whose marching orders are to build criminal cases around such charges.
He added that other strike forces had been formed to focus on assaults on law enforcement and members of the media.
"The range of criminal conduct is really... unmatched in any type of scenario that we've seen," Sherwin said, noting it runs the gamut from "simple trespass" and "theft of mail" to "felony murder and even civil rights excessive force."
Investigators are combing social media images that showed hundreds of people swarming the building, attacking police, stealing computers and artifacts and smashing windows.
Steven D'Antuono, the assistant director in charge for the FBI's Washington, D.C. office, said the bureau has been combing through more than 100,000 photos, video and other tips it has received since last week.
The FBI has been releasing photos of suspects and seeking help from the public. Recently, it released images of someone who is suspected of planting pipe bombs at the headquarters of the Democratic and Republican national committees.
Senator Bill Cassidy, Republican from Louisiana, on Tuesday tweeted photos he said he had received from Capitol Police and added that the man pictured was wanted for questioning in connection with the murder of Capitol Police officer Brian Sicknick.
D'Antuono declined to comment on whether the man in the photo is in fact a suspect, telling reporters the investigation was ongoing and the FBI was reviewing numerous videos.
Comments
It is highly likely that this investigation will track down and identify the person or persons who murdered the police officer. Everyone they identify as being in the Capitol building, and they can do this by checking which cell phones pinged into the Capitol cell transmitters, will be fingerprinted and DNA tested to match against any evidence found at the scene and interrogated about their involvement in the murder. Those who had no part in it but know who did will soon spill the beans.