Former White House chief strategist Steve Bannon surrendered on Monday morning to federal authorities to face contempt charges after defying a subpoena from a US House of Representatives committee investigating the January 6 insurrection at the US Capitol.
A defiant Mr Bannon was taken into FBI custody before appearing before Magistrate Judge Robin Meriweather.
Ms Meriweather imposed several conditions on Mr Bannon before releasing him, including requiring him to check in weekly with court officials and surrender his US passport.
Mr Bannon did not enter a plea during the hearing, with an arraignment instead scheduled for Thursday before US District Judge Carl Nichols.
"This is all noise," he said of his indictment as he arrived at the FBI's Washington field office.
"I want you guys to stay focused on the message," he said, promoting his website, War Room.
"We're taking down the [Joe] Biden regime."
Indicted by a federal grand jury last week, Mr Bannon was charged with one count of refusing to appear for a deposition and an additional charge of refusing to provide documents related to the investigation, a statement released by the US department of Justice said.
"Steve Bannon's indictment should send a clear message to anyone who thinks they can ignore the Select Committee or try to stonewall our investigation: no one is above the law," said committee chair Bennie Thompson and vice chair Liz Cheney in a statement.
Contempt of Congress is a misdemeanor punishable by up to one year in jail along with a monetary fine.
The US House Select Committee believes Mr Bannon possesses relevant information pertaining to events surrounding the January 6 insurrection at the Capitol.
The former chief strategist previously claimed that former US president Donald Trump had instructed him not to appear before the committee on the grounds of executive privilege, which permits presidents to keep certain communications with aides confidential.
He left his post as senior adviser to Mr Trump in 2017.
Mr Bannon is one of more than 30 people close to Mr Trump who have been ordered by the House committee to testify about the run-up to January 6, when a mob of Trump supporters stormed the Capitol in a failed attempt to prevent formal congressional certification of Mr Trump's election loss to Mr Biden.
The indictment came as a second expected witness, former White House chief of staff Mark Meadows, defied his own subpoena from the committee on Friday.
Mr Meadows's lawyer argued it would be inappropriate for him to speak before the committee until a court delivers a ruling on Mr Trump's claim of executive privilege over materials related to the insurrection.
House investigators hope the charges against Mr Bannon will motivate other witnesses including Mr Meadows to testify.
Committee member Adam Schiff on Sunday said that the committee would “move quickly” to refer Mr Meadows for criminal contempt for not co-operating with the investigation.
Mr Trump is fighting the committee's request for documents from his administration now in the National Archives.
After Mr Biden, as serving president, waived privilege over the documents, the federal court in Washington rejected Mr Trump's challenge.
Mr Trump has since appealed, and the case, which could go to the Supreme Court, is now focused on never-before-tested clashing privilege stances by a serving and former president.
Agencies contributed to this report