Stewart Rhodes, the leader of the far-right Oath Keepers militia, and one of his subordinates were convicted on Tuesday of seditious conspiracy as a jury found them guilty of seeking to keep former President Donald J. Trump in power through a plot that started after the 2020 election and culminated in the mob attack on the Capitol.
But the jury in Federal District Court in Washington found three other defendants in the case not guilty of sedition and acquitted Mr. Rhodes of two separate conspiracy charges.
The split verdicts, coming after three days of deliberations, were nonetheless a victory for the Justice Department and the first time in nearly 20 trials related to the Capitol attack that a jury decided that the violence that erupted on Jan. 6, 2021, was the product of an organized conspiracy.
Seditious conspiracy is the most serious charge brought so far in any of the 900 criminal cases stemming from the vast investigation of the Capitol attack, an inquiry that could still result in scores, if not hundreds, of additional arrests. It carries a maximum penalty of 20 years in prison.
Mr. Rhodes was convicted of sedition along with Kelly Meggs, who ran the Florida chapter of the Oath Keepers at the time of the Capitol attack. Three other defendants in the case — Kenneth Harrelson, Jessica Watkins and Thomas Caldwell — were found not guilty of sedition.