WASHINGTON — A member of the far-right nationalist Proud Boys was in communication with a person associated with the White House in the days just before the Jan. 6 assault on the Capitol, according to a law enforcement official briefed on the investigation.
Location, cellular and call record data revealed a call tying a Proud Boys member to the Trump White House, the official said. The F.B.I. has not determined what they discussed, and the official would not reveal the names of either party.
The connection revealed by the communications data comes as the F.B.I. intensifies its investigation of contacts among far-right extremists, Trump White House associates and conservative members of Congress in the days before the attack.
The same data has revealed no evidence of communications between the rioters and members of Congress during the deadly attack, the official said. That undercuts Democratic allegations that some Republican lawmakers were active participants that day.
Separately, Enrique Tarrio, a leader of the far-right nationalist Proud Boys, told The New York Times on Friday that he called Roger J. Stone Jr., a close associate of former President Donald J. Trump’s, while at a protest in front of the home of Senator Marco Rubio, Republican of Florida. During the protest, which occurred in the days before the Capitol assault, he put Mr. Stone on speaker phone to address the gathering.
A law enforcement official said that it was not Mr. Tarrio’s communication with Mr. Stone that was being scrutinized, and that the call made in front of Mr. Rubio’s home was a different matter. That two members of the group were in communication with people associated with the White House underscores the access that violent extremist groups like the Proud Boys had to the White House and to people close to the former president.
Mr. Stone denied “any involvement or knowledge of the attack on the Capitol” in a statement last month to The Times.
Mr. Tarrio was arrested in Washington on Jan. 4 on charges of destruction of property for his role in the burning of a Black Lives Matter banner that had been torn from a historic Black church during a protest in Washington in December. He was asked to leave the city, and was not present when the Capitol was attacked. His case is pending.
The Justice Department has charged more than a dozen members of the Proud Boys with crimes related to the attack, including conspiracy to obstruct the final certification of President Biden’s electoral victory and to attack law enforcement officers.
In court papers, federal prosecutors have said groups of Proud Boys also coordinated travel to Washington and shared lodging near the city, with the intent of disrupting Congress and advancing Mr. Trump’s efforts to unlawfully maintain his grip on the presidency.
The communication between the person associated with the White House and the member of the Proud Boys was discovered in part through data that the F.B.I. obtained from technology and telecommunications companies immediately after the assault.
Court documents show F.B.I. warrants for a list of all the phones associated with the cell towers serving the Capitol, and that it received information from the major cellphone carriers on the numbers called by everyone on the Capitol’s cell towers during the riot, three officials familiar with the investigation said.
The F.B.I. also obtained a “geofence” warrant for all the Android devices that Google recorded within the building during the assault, the officials said. A geofence warrant legally gives law enforcement a list of mobile devices that are able to be identified in a particular geographic area. Jill Sanborn, the head of counterterrorism at the F.B.I., testified before a Senate panel on Wednesday that all the data the F.B.I. had gathered in its investigation into the riot was obtained legally through subpoenas and search warrants.
Although investigators have found no contact between the rioters and members of Congress during the attack, those records have shown evidence in the days leading up to Jan. 6 of communications between far-right extremists and lawmakers who were planning to appear at the rally featuring Mr. Trump that occurred just before the assault, according to one of the officials.
The Justice Department is examining those communications, but it has not opened investigations into any members, the official said. A department spokesman declined to comment.
The F.B.I. did, however, say on Thursday that it had arrested a former State Department aide on charges related to the attack, including unlawful entry, violent and disorderly conduct, obstructing Congress and law enforcement, and assaulting an officer with a dangerous weapon.
The former midlevel aide, Federico G. Klein, who was seen in videos assaulting officers with a stolen riot shield, was the first member of the Trump administration to face criminal charges in connection with the storming of the Capitol. His lawyer declined to comment on Friday.
Right-wing extremists, including members of the Oath Keepers, a militia group that mainly comprises former law enforcement and military personnel, have been working as security guards for Republicans and for Mr. Trump’s allies, such as Mr. Stone.
Mr. Stone, who was pardoned by Mr. Trump after refusing to cooperate with the investigation into the Trump campaign’s contacts with Russian intelligence, has known Mr. Tarrio for some time and used Oath Keepers as bodyguards before and on the day of the assault on the Capitol.
The Justice Department is looking into communications between Mr. Stone and far-right extremists to determine whether he played any role in plans by extremists to disrupt the certification on Jan. 6, according to two people familiar with the matter who were not authorized to speak about the investigation.
Should investigators find messages showing that Mr. Stone had any connection to such plans, they would have a factual basis to open a full criminal investigation into him, the people said.
Mr. Stone said last month that he was “provided voluntary security by the Oath Keepers,” but noted that their security work did not constitute evidence that he was involved in, or informed about, plans to attack Congress. He reiterated an earlier statement that anyone involved in the attack should be prosecuted.
The Justice Department has charged more than 300 people with crimes stemming from the Jan. 6 assault. It has used evidence gathered in its broad manhunt for assailants — including information from cellular providers and technology companies — to help piece together evidence of more sophisticated crimes, like conspiracy.
It is also looking at possible charges of seditious conspiracy, according to two people familiar with the investigation.
Katie Benner and Adam Goldman reported from Washington, and Alan Feuer from New York. Jennifer Valentino-DeVries contributed reporting from New York.