Far-right Proud Boys member Jeremy Joseph Bertino, second from left, joins other supporters of President Trump at a rally Dec. 12, 2020, in Washington. Luis M. Alvarez/Associated Press, file

WASHINGTON — A North Carolina man pleaded guilty Thursday to plotting with other members of the far-right Proud Boys to violently stop the transfer of presidential power after the 2020 election, making him the first member of the extremist group to plead guilty to a seditious conspiracy charge.

Jeremy Joseph Bertino, 43, has agreed to cooperate with the Justice Department’s investigation of the role that Proud Boys leaders played in the mob’s attack on the Capitol on Jan. 6, 2021, a federal prosecutor said.

Bertino’s cooperation could ratchet up the pressure on other Proud Boys charged in the siege, including former national chairman Henry “Enrique” Tarrio.

The guilty plea comes as the founder of the another extremist group, the Oath Keepers, and four associates charged separately in the Jan. 6 attack stand trial on seditious conspiracy – a rarely used Civil War era offense that calls for up to 20 years behind bars.

Bertino traveled to Washington with other Proud Boys in December 2020 and was stabbed during a fight, according to court documents. He was not in Washington for the Jan. 6 riot because he was still recovering from his injuries, court papers say.

Bertino participated in planning sessions in the days leading up to Jan. 6 and received encrypted messages as early as Jan. 4 indicating that Proud Boys were discussing possibly storming the Capitol, according to authorities.

A statement of offense filed in court says that Bertino understood the Proud Boys’ goal in traveling to Washington was to stop the certification of Joe Biden’s victory and that the group was prepared to use force and violence if necessary to do so.

On Jan. 6, Bertino applauded the insurrection from afar and sent messages encouraging other Proud Boys to keep pushing toward the Capitol.

“DO NOT GO HOME. WE ARE ON THE CUSP OF SAVING THE CONSTITUTION,” he wrote on a social media account. That night, he messaged Tarrio, “You know we made this happen.”

Bertino also pleaded guilty to a charge of unlawfully possessing firearms in March 2022 in Belmont, North Carolina. U.S. District Judge Timothy Kelly agreed to release Bertino pending a sentencing hearing, which wasn’t immediately scheduled.

Justice Department prosecutor Erik Kenerson said sentencing guidelines for Bertino’s case recommend a prison sentence ranging from four years and three months to five years and three months.

A trial is scheduled to start in December for Tarrio and four other members charged with seditious conspiracy: Ethan Nordean, Joseph Biggs, Zachary Rehl and Dominic Pezzola. The charging document for Bertino’s case names those five defendants and a sixth Proud Boys member as his co-conspirators.

Tarrio’s case is among the most serious charged in the attack, which sent lawmakers running and left dozens of officers bloodied and bruised.

Nayib Hassan, one of Tarrio’s attorneys, said Bertino’s cooperation doesn’t change the landscape for his client’s case. He described Bertino as “just another individual who is going to be testifying.” Tarrio is “still looking forward to his day at trial,” Hassan added.

The indictment in Tarrio’s case alleges that the Proud Boys held meetings and communicated over encrypted messages to plan for the attack in the days leading up to Jan. 6. On the day of the riot, authorities say Proud Boys dismantled metal barricades set up to protect the Capitol and mobilized, directed and led members of the crowd into the building.

Video testimony by Bertino was featured in June at the first hearing by the House committee investigating Jan. 6. The committee showed a clip of Bertino saying that the group’s membership “tripled, probably” after Trump’s comment at a presidential debate that the Proud Boys should “stand back and stand by.”

Tarrio wasn’t in Washington on Jan. 6, but authorities say he helped put into motion the violence that day. Police arrested Tarrio in Washington two days before the riot and charged him with vandalizing a Black Lives Matter banner at a historic Black church during a protest in December 2020. Tarrio was released from jail on Jan. 14 of this year after serving his five-month sentence for that case.

More than three dozen people charged in the Capitol riot have been identified by federal authorities as leaders, members or associates of the Proud Boys. Two – Matthew Greene and Charles Donohoe – pleaded guilty to conspiring to obstruct an official proceeding, the Jan. 6 joint session of Congress for certifying the Electoral College vote.

Proud Boys members describe the group as a politically incorrect men’s club for “Western chauvinists.” They have brawled with antifascist activists at rallies and protests. Vice Media co-founder Gavin McInnes, who founded the Proud Boys in 2016, sued the Southern Poverty Law Center for labeling it as a hate group.

Nordean, of Auburn, Washington, was a Proud Boys chapter president and a member of the group’s national “Elders Council.” Biggs, of Ormond Beach, Florida, is a self-described Proud Boys organizer. Rehl was president of the Proud Boys chapter in Philadelphia. Pezzola is a Proud Boys member from Rochester, New York.