PHOENIX (AP) — A Georgia man affiliated with the far-right Oath Keepers militia group became the second Capitol rioter to plead guilty to seditious conspiracy for his actions leading up and through the Jan. 6, 2021 insurrection.

The sentencing guidelines for Brian Ulrich, who also pleaded guilty to obstructing an official proceeding, were estimated to be 5 ¼ years to 6 ½ years in prison.

Authorities say Ulrich participated in encrypted chats with other people affiliated with the Oath Keepers in the days before the riot, rode toward the Capitol with others in golf carts on that day, marched on the grounds in a military “stack” formation, taunted police officers who were guarding the building and also entered the Capitol as hundreds of former President Donald Trump’s supporters sought to block the certification of President Joe Biden’s victory.

Asked by the judge whether he was pleading guilty because he was in fact guilty of the charges, Ulrich answered, “Yes, your honor.”

The 44-year-old from Guyton, Georgia, agreed to cooperate with authorities investigating the riot, including testifying before a grand jury.

The seditious conspiracy prosecution is the boldest publicly known attempt so far by the government to prosecute those who attacked the U.S. Capitol. The group’s founder, Stewart Rhodes, and eight others have pleaded not guilty to seditious conspiracy and other charges.

A conviction under the seditious conspiracy charge carries a maximum penalty of 20 years, compared with five years on the lesser conspiracy charge that others associated with the militia group are facing.

Those charged with seditious conspiracy are accused of working together to use force to stop the peaceful transfer of presidential power. Authorities say participants discussed their plans in encrypted chats, traveled to the nation’s capital from across the country, organized into teams, used military tactics, stashed weapons in case they felt they were needed, and communicated with each other during the Jan. 6 riot.

While four other people connected with the Oath Keepers have pleaded guilty to obstruction of Congress and the lesser conspiracy charge, Ulrich is the second person to plead guilty to seditious conspiracy. Joshua A. James of Arab, Alabama, pleaded guilty to the charge last month.

Prosecutors say the group set up a “quick reaction force,” or QRF, that kept guns at a hotel in nearby Arlington, Virginia, and that they were prepared to bring the weapons into Washington if Rhodes or associates believed the need arose. Days before the attack, one defendant suggested getting a boat to ferry weapons across the Potomac River. In the end, the QRF teams didn’t bring guns into Washington.

More than 780 people have been charged with federal crimes related to the Jan. 6 riot. Over 250 of them have pleaded guilty, mostly to misdemeanors. About 160 of them have been sentenced.