The F.B.I. had as many as eight informants inside the far-right Proud Boys in the months surrounding the storming of the Capitol on Jan. 6, 2021, recent court papers indicate, raising questions about how much federal investigators were able to learn from them about the violent mob attack both before and after it took place.
The existence of the informants came to light over the past few days in a flurry of veiled court filings by defense lawyers for five members of the Proud Boys who are set to go on trial next month on seditious conspiracy charges connected to the Capitol attack.
In the papers, some of which were heavily redacted, the lawyers claimed that some of the information the confidential sources had provided to the government was favorable to their efforts to defend their clients against sedition charges and was improperly withheld by prosecutors until several days ago.
In a sealed filing quoted by the defense, prosecutors argued that hundreds of pages of documents related to the F.B.I. informants were neither “suppressed” by the government nor directly relevant to the case of the Proud Boys facing sedition charges: Enrique Tarrio, the group’s former leader; Joseph Biggs; Ethan Nordean; Zachary Rehl; and Dominic Pezzola.
Because all of the material remains under a highly restrictive protective order, it is not possible to know what the informants told the government about the Proud Boys’ role in the Capitol attack or how that information might affect the outcome of the trial.
A closed court hearing was held on Monday to discuss the informants in Federal District Court in Washington. Lawyers for the Proud Boys have asked Judge Timothy J. Kelly, who is overseeing the case, to dismiss the indictment — or at least delay the trial to give them more time to investigate the newly revealed informants.
Judge Kelly made no decision at the hearing, according to a notice placed on the docket after the proceeding ended. Because it was sealed, journalists were not allowed in the courtroom.
The dispute about the informants in the Proud Boys came on the heels of revelations that the F.B.I. also had a well-placed source in the inner circle of Stewart Rhodes, the leader of the Oath Keepers militia, another far-right group that took part in the Capitol attack.
Last week, lawyers for Mr. Rhodes and four other Oath Keepers who are being tried on sedition charges planned to call the informant — Greg McWhirter, the group’s former vice president — as a defense witness, believing that his testimony would bolster their case. But on the eve of his planned appearance, Mr. McWhirter suffered a heart attack and the defense put other witnesses in his place.
Questions about informants reporting to the government from inside extremist groups have been raised repeatedly throughout the Justice Department’s sprawling investigation of the Capitol attack. They have included concerns about why the informants were not able to give the government advanced warning about plans to storm the Capitol on Jan. 6 or seemingly to corroborate accusations after the fact that the groups conspired in plotting the attack.
Former F.B.I. officials say there might have been gaps in what bureau intelligence analysts had told agents to ask their informants. Analysts at the bureau are supposed to help agents connect the intelligence dots to provide a clearer picture of threat activity. The F.B.I.’s intelligence directorate was created after Sept. 11 to help thwart terrorism and other threats.
It remains unclear what sorts of questions the F.B.I. was asking its informants in the Proud Boys and how focused the bureau was on the group’s activities to undermine the results of the elections as Jan. 6 drew near. Previous court papers have suggested that some Proud Boys — including Mr. Biggs — were recruited by the F.B.I. before the election to provide information about their adversaries in the leftist movement known as antifa.
Last year, The New York Times revealed the existence of an informant in the Kansas City chapter of the Proud Boys who took part in the storming of the Capitol with a group of his compatriots. After the attack, the informant told his handlers in interviews that he was not aware of a premeditated plan to break into the building on Jan. 6, although as a relatively low-level member of the group it is possible that he was simply not privy to the making of such plans.
Right-wing media figures and Republican politicians have often sought to use the issue of F.B.I. informants in extremist groups to suggest that the bureau had a hand in guiding or encouraging the attack on the Capitol in a way that entrapped other rioters. No evidence has surfaced suggesting that the F.B.I. played any role in the attack.
But the lawyers for the Proud Boys have made entirely different claims, arguing that the information the confidential sources provided to prosecutors appears to be exculpatory and could contradict the government’s chief allegation in the case: that their clients went to Washington on Jan. 6 with a plan in place to storm the Capitol and disrupt the transfer of power from President Donald J. Trump to Joseph R. Biden Jr.
The newly disclosed material called into question “whether a Proud Boy conspiracy plan to obstruct the Biden-Harris vote certification or to commit sedition ever existed or could have existed,” J. Daniel Hull, Mr. Biggs’s lawyer, wrote in papers filed on Monday.
The notion of whether there was a predetermined plan to attack the Capitol or whether the violence that erupted there on Jan. 6 was more spontaneous will be one of the key disputes when the Proud Boys’ trial — now scheduled to start on Dec. 12 — goes in front of a jury. To prove seditious conspiracy, prosecutors will have to show that the defendants knowingly entered into an agreement to use force to stop the lawful transfer of power after the 2020 election.
If the information provided by the informants is indeed exculpatory, the lawyers for the Proud Boys could in theory call some of them to testify at the trial and rebut the government’s charges.
A similar dynamic has been playing out in recent days in the Oath Keepers sedition trial, which could go to the jury as early as this week. A central part of the defense’s strategy in the case has been to introduce evidence that the Oath Keepers had no explicit plan to attack the Capitol.