(CNN)At least 150 people have now been charged by federal prosecutors in connection with the January 6 insurrection at the Capitol, according to a CNN review of court records and Justice Department announcements, as a top prosecutor said charges of sedition are not out of the question.
The milestone of 150 charged in the riot comes less than a day after the US House transmitted to the Senate an article of impeachment against former President Donald Trump for inciting insurrection. Trump will now face a trial in the same Senate chamber that rioters -- aiming to stop Congress' certification of President Joe Biden's electoral win -- breached minutes after members of the Senate had been hurried to safety.
Investigators have used 500 grand jury subpoenas and search warrants to gather information in the sweeping, unparalleled investigation, Michael Sherwin, the top US prosecutor in Washington, said in a news conference Tuesday.
Sedition, among other charges, is "what we're trying to build toward," Sherwin said.
The dragnet has stretched across the country, with arrests in Florida, California, New Hampshire and Hawaii.
Many of the at least 150 defendants that CNN has identified have been charged with entering a restricted building without lawful authority and violent entry and disorderly conduct in the Capitol. The more serious charges have ranged from theft of government property, conspiracy, interstate threats, to assault on law enforcement.
The Justice Department now has more than 400 subjects in its investigation, Sherwin said Tuesday.
The FBI's Steven D'Antuono said the agency has received 200,000 digital media tips from the public about the insurrection.
Law enforcement officials have told CNN they expect hundreds of more riot participants to be arrested in the future. But they also say investigators have begun to focus on the more complex cases, like extremist groups that participated in the attack, and less on the low-hanging fruit arrests and charges.
Sherwin said prosecutors are building toward charging Capitol riot defendants with sedition, as well as looking groups from various states who coordinated coming to the Capitol and in other long-term planning.
"We are going to reach a plateau I think in the very near future ... and the plateau will involve in looking at the more complicated conspiracy cases related to possible coordination among militia groups," Sherwin said.
So far, the Justice Department had been bringing cases against people largely identified on the Internet, for violent entry and trespassing, and some violence toward police and weapons charges.
The cases that have resulted in arrests already are progressing slowly, with many of the defendants going before federal judges in their home states before they move to Washington, DC. There's a bottleneck as well in the DC federal court, and many haven't yet seen a judge or had their charges formally indicted. The Justice Department has agreed to let many of the defendants be released as they await trials, with various restrictions including stay-away-orders from DC.
A few defendants, such as men who allegedly threatened to kill lawmakers or brought bombs to the Capitol, will stay in detention, judges have ruled, and a handful are sitting in jail as federal judges review their detention decisions.
Over the course of the riot, prosecutors say approximately 81 Capitol Police and 58 DC Metro police officers were assaulted. Capitol Hill officer Brian Sicknick died responding to the riot, "due to injuries sustained while on-duty," according to a Capitol Police statement.
More charges to come
D'Antuono, the FBI assistant director in Washington, DC, told reporters Tuesday that investigators are still looking for Capitol rioters who assaulted law enforcement officers and the person or people responsibility for planting pipe bombs outside of Republican and Democratic party headquarters buildings.
The agency is still offering a $75,000 reward for help in the pipe bomb investigation, D'Antuono said.
"It is challenging, it is complex and it is big ... at the FBI, we do big, we do challenging, we do complex," D'Antuono said in a news conference. "This case is unique in its magnitude and number of subjects."
The flurry of arrests and charges takes place against the backdrop of the new Biden administration beginning to take the reins of the Justice Department, which could speak to their continued absence.
Filing such major charges would likely require sign-off from the new Biden administration officials at Justice headquarters, which is currently led by acting Attorney General Monty Wilkinson and acting Deputy Attorney General John Carlin. Senate confirmation for Biden's pick for Attorney General Merrick Garland and deputy Attorney General Lisa Monaco is likely weeks away.
Sedition is a Civil War-era law that brings up to 20-year penalties for plotting to overthrow the US government and to use force to oppose US government authority or to delay the execution of a US law. Last summer, amid street protests following the police killing of George Floyd, then-Attorney General William Barr encouraged federal prosecutors to use the law against leftist protesters, a move that no one made.
This story has been updated with information from the FBI and Justice Department.