WASHINGTON — F.B.I. agents and prosecutors investigating the Jan. 6 riot at the Capitol have increasingly shifted their attention to dangerous right-wing extremist groups, arresting several people in recent days suspected of taking part in the violence and of possessing ties to notorious militias such as the Oath Keepers and the Three Percenters.
The spate of arrests helps fill in a more complete picture of the mob that stormed the Capitol after being incited by President Trump on Jan. 6 in an attempt to stop Congress from certifying the Electoral College victory of President-elect Joseph R. Biden Jr.
The arrests, in Ohio, Colorado, Indiana and Texas, came as investigators gathered evidence to determine whether any of the groups had planned ahead of time to attack the Capitol. Videos and photos have revealed chilling scenes of rioters weaving through the mobs inside the building in tight formation, wearing tactical gear, carrying restraints and using hand signals and hand radios to communicate.
Militia groups have a long history of taking part in anti-government events and right-wing political protests. The Oath Keepers are an anti-government, pro-gun militia composed largely of former law enforcement and military veterans “who believe that the federal government has been co-opted by a shadowy conspiracy that is trying to strip American citizens of their rights,” according to the F.B.I. The name of the Three Percenters, an anti-government group, is a reference to the purported 3 percent of the American colonial population that rose up to fight the British Army in the Revolution.
Washington remained on edge on Monday as the Capitol Police issued a lockdown order at the Capitol for 45 minutes after a small fire was spotted in the area. Thousands of National Guard troops lined the heavy steel fences surrounding the building with unloaded assault rifles and others patrolled as the area remained under heavy security two days ahead of the inauguration.
The pace of arrests and criminal charges continued unabated with F.B.I. agents fanning out across the country to track down rioting suspects. Agents have made at least 70 arrests, opened more than 300 investigations and gathered about 140,000 media tips as law enforcement officials monitored social media for word of more unrest or coordinated attacks.
The highly visible investigation has set off alarm bells among far-right groups, already prone to conspiratorial thinking, with some now worried that online chatter about protests and other pro-Trump activities is a trap set by the government to apprehend them, according to a person briefed on intelligence about the groups.
Prosecutors were making a top priority of focusing on militia members and other extremists and would build more serious sedition and murder cases against such groups if the evidence permits, Michael R. Sherwin, the acting U.S. attorney in Washington, said last week.
“All of these extremist groups are being looked at in terms of their participation at the Capitol,” he told reporters.
The federal authorities have prioritized not only militias but others who were involved in attacking police officers. The F.B.I. has also arrested members of the Proud Boys, a far-right nationalist group.
On Sunday evening, Donovan Crowl, 50, a former U.S. Marine, and Jessica Watkins, 38, an Army veteran, surrendered to the authorities in Ohio after they published photos of themselves on social media wearing combat gear and saying that they had stormed the Capitol. They were charged in a criminal complaint with unlawful entry, disorderly conduct and obstructing an official proceeding.
The F.B.I. said Ms. Watkins considered herself the commander of the Ohio State Regular Militia, which is affiliated with the Oath Keepers. In a social media post by Ms. Watkins, Mr. Crowl was depicted with the caption: “One of my guys at the Stop the Steal Rally today.”
Federal prosecutors also unsealed charges this weekend against Robert Gieswein, 24, of Woodland Park, Colo., who they say is affiliated with the Three Percenters.
Mr. Gieswein, who runs a private paramilitary training group called the Woodland Wild Dogs, was among the early wave of invaders to breach the Capitol, court papers said. Photographs from the attack show him clad in a military vest, goggles and an Army-style helmet, wrestling with Capitol Police officers to remove metal barricades and brandishing a baseball bat. In a criminal complaint, prosecutors cited a video of Mr. Gieswein encouraging other rioters as they smashed a window at the Capitol with a wooden board and a plastic shield and then climbing through the broken glass into the building.
Mr. Gieswein was photographed inside the building with another suspect, Dominic Pezzola, a former Marine and member of the Proud Boys, who was charged last week.
After the assault, Mr. Gieswein said in a news documentary interview that he attacked the Capitol to “get the corrupt politicians out of office,” according to court papers, adding, “They have completely destroyed our country and sold them to the Rothschilds and Rockefellers.”
At least four people suspected of being in the Oath Keepers have been arrested, including Jon Schaffer, an Indiana musician, who surrendered to the F.B.I. He was seen donning a hat that said “Oath Keepers Lifetime Member.” Larry R. Brock, a retired Air Force lieutenant colonel from Texas, was videotaped inside the Senate gallery wearing a helmet and holding flex cuffs. He apparently aligned himself with both the Oath Keepers and the Three Percenters.
