Hundreds of convictions, but a major mystery is still unsolved 3 years after the Jan. 6 Capitol riot

Rioters walk on the West Front at the U.S. Capitol on Jan. 6, 2021, in Washington. Democracy scholars are warning that political parties must accept the results of fair elections, reject violence and break ties to extremists. (AP Photo/Julio Cortez)

U.S. Attorney for the District of Colombia Matthew Graves speaks about the unfolding of the January 6 attack on the Capitol during a presentation ahead of this year’s third anniversary in Washington, Thursday, Jan. 4, 2024. (AP Photo/Susan Walsh)

WASHINGTON — Members of far-right extremist groups. Former police officers. An Olympic gold medalist swimmer. And active duty U.S. Marines.