A North Carolina man pleaded guilty on 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 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 6 January 2021, a federal prosecutor said. Judge Timothy Kelly agreed to release Bertino pending a sentencing hearing that was not immediately scheduled.

Bertino also pleaded guilty to a charge of unlawfully possessing firearms in March in Belmont, North Carolina. Kelly accepted his guilty plea to both charges during a brief hearing after the case against Bertino was filed on Thursday.

Prosecutor Erik Kenerson said estimated sentencing guidelines for Bertino’s case recommend a prison sentence ranging from four years and three months to five years and three months. The civil war-era seditious conspiracy charge carries a maximum sentence of 20 years in prison.

Former Proud Boys national chairman Henry “Enrique” Tarrio and four other group members also have been charged with seditious conspiracy for what prosecutors say was a coordinated attack on the Capitol to stop Congress from certifying Joe Biden’s 2020 electoral victory.

A trial for Ethan Nordean, Joseph Biggs, Zachary Rehl and Dominic Pezzola is scheduled to start in December.

A trial started this week in Washington for the seditious conspiracy case against the founder of the Oath Keepers and other members of the anti-government militia group for their participation in the attack.

More than three dozen people charged in the Capitol siege have been identified by federal authorities as leaders, members or associates of the Proud Boys.

Two of them Matthew Greene and Charles Donohoe pleaded guilty to conspiring to obstruct an official proceeding, the January 6 joint session of Congress for certifying the electoral college vote.