Washington(CNN) A third member of the far-right Oath Keepers group who stormed the US Capitol in a unified military formation pleaded guilty on Tuesday afternoon and will cooperate with prosecutors, according to court records.
Caleb Berry, 20, pleaded guilty in DC District Court to two felonies -- conspiracy and obstruction of a congressional proceeding -- for his role in temporarily stopping the Electoral College process on January 6.
The guilty plea and cooperation deal are a major achievement for federal prosecutors as they continue to aggressively probe right-wing groups that planned for violence in DC on January 6. They have already secured the cooperation of two other co-conspirators in the major case against the Oath Keepers.
Nearly 20 people affiliated with the group have been charged, and prosecutors are scrutinizing the group's leader as well.
According to charging documents, Berry admitted that he dropped off weapons at a hotel in Arlington, Virginia, on January 5. This was part of a "quick reaction force" that the Oath Keepers planned to deploy into DC if things became violent. (Lawyers for other defendants in the case have said the weapons were to protect against Antifa, not to attack the Capitol.)
Berry also "traveled to and then observed the restricted Capitol grounds" on January 5, one day before the attack, according to charging documents. Prosecutors will surely be asking him for information about pre-planning and surveillance that the Oath Keepers did near the Capitol before the January 6 attack.
As part of his plea deal, the agreed-upon sentencing guidelines say Berry could face about four to five years in prison, though that will ultimately be decided by the judge. If he proves incredibly helpful to prosecutors, he could get a much lighter sentence. He has no criminal history, and judges often show some leniency to first-time offenders.
Berry also agreed to pay $2,000 to repair damage to the Capitol, which is the standard amount that prosecutors have inserted into plea deals for felony defendants like Berry.
Two other defendants in the marquee Oath Keepers conspiracy case, Graydon Young of Florida and Mark Grods of Alabama, have already pleaded guilty and are cooperating.
A fourth rioter with ties to the far-right group, heavy metal guitarist Jon Schaffer, pleaded guilty in a separate case and is also cooperating, but he wasn't part of the group of Oath Keepers who moved together around and inside the Capitol that day.
Three people have now been sentenced for their roles in the Capitol riot, and about 20 people have pleaded guilty so far and are awaiting sentencing. Countless others are expected to plead guilty and are still negotiating deals with prosecutors. But some rioters have indicated that they want to go to trial, a drawn-out process that is certain to drag into 2022.
This story has been updated with further developments Tuesday.