Jan. 6 Defendant Coordinated Volunteers to Help Glenn Youngkin

In the election last fall that sent Glenn Youngkin to the Virginia governor’s office and propelled him to G.O.P. stardom, the state and local Republican Party tasked Joseph Brody with coordinating volunteers to knock on doors of potential Youngkin voters in the state’s strategically crucial northern suburbs.

But eight months earlier, Mr. Brody had been immersed in the Jan. 6 attack at the U.S. Capitol, according to the F.B.I., which said that he assaulted a police officer with a metal barricade and breached several restricted areas, including the Senate floor and the office of Speaker Nancy Pelosi.

Now, Mr. Brody, 23, who the F.B.I. said was associated with the white nationalist group America First, is facing felony and misdemeanor charges for his role. The candidate he would go on to help, Mr. Youngkin, tried during his campaign to keep himself at arm’s length from former President Donald J. Trump, and he called the Jan. 6 riot a “blight on our democracy.”

Shortly after Mr. Brody’s arrest last month, an image scraped from the internet by online sleuths who call themselves “Sedition Hunters” showed a man in a MAGA hat holding a high-powered rifle in front of a Nazi flag, with a bandanna concealing his face. The group, which has provided information that has helped law enforcement officials make hundreds of arrests related to Jan. 6, said the man in the photo was Mr. Brody.

A public defender listed for Mr. Brody did not respond to several requests for comment. Messages sent to an email account for Mr. Brody went unanswered. There was no answer at a phone number listed for him.

Mr. Youngkin’s office referred questions about Mr. Brody to Kristin Davison, a political consultant for the governor, who said in an email on Friday that Mr. Brody “did not work for or with the Youngkin campaign.”

The Fairfax County Republican Committee twice listed Mr. Brody, who is from Springfield, Va., in Fairfax, as helping to coordinate a volunteer effort to knock on doors for “Team Youngkin.” When asked about those online listings, Ms. Davison said, “Those are not posts from the Youngkin campaign.”

Mr. Youngkin’s campaign logo appeared on both pages, which included an official email address associated with the Republican Party of Virginia for Mr. Brody.

“Mr. Brody was employed by the party as a door-knocker for one month last fall,” Ellie Sorensen, a state G.O.P. spokeswoman, said in an email on Monday. “He has not been employed by the Republican Party of Virginia for over a year.”

Ms. Sorensen did not comment further about the charges against Mr. Brody or what had led to the end of his employment with the party.

The Fairfax Republicans did not respond to multiple requests for comment.

According to a criminal affidavit, Mr. Brody recorded and photographed senators’ desks during the Capitol attack, in which he wore a neck gaiter with an American flag pattern. Later, he “assisted another rioter in using a metal barricade against a Capitol Police officer, knocking the officer back as he attempted to secure the north door,” an F.B.I. agent said in the affidavit.

Federal investigators said Mr. Brody had previously met four other men who were recently charged in the attack at an event held by America First, whose followers are known as Groypers. The movement’s leader, Nicholas J. Fuentes, a white supremacist who has been denounced by conservative organizations as a Holocaust denier and a racist, was issued a subpoena by the congressional committee investigating the Jan. 6 attack.

In one photograph that a group of Sedition Hunters said it had obtained of Mr. Brody, a young political canvasser holds a campaign sign for Mr. Youngkin. The group contrasted that image with other postings it said were from Mr. Brody’s social media accounts, some of which showed Nazi symbols and diatribes against women.

Luke Broadwater contributed reporting.