A former State Department aide in President Donald Trump's administration has been charged with participating in the deadly siege at the Capitol and assaulting officers who were trying to guard the building, court papers show.

It’s the first known case to be brought against a Trump appointee in the Jan. 6 insurrection, which led to Trump's historic second impeachment.

Federico Klein, who also worked for Trump's 2016 campaign, was seen wearing a “Make America Great Again" hat amid the throng of people in a tunnel trying to force their way into the Capitol on Jan. 6, the papers say. Klein pushed his way toward the doors, where, authorities say, “he physically and verbally engaged" with officers trying to keep the mob back.

Klein was seen on camera violently shoving a riot shield into an officer and inciting the crowd as it tried to storm past the police line, shouting, “We need fresh people, we need fresh people,” according to the charging documents.

As the mob struggled with police in the tunnel, Klein pushed the riot shield, which had been stolen from an officer, in between the Capitol doors, preventing police from closing them, authorities say. Eventually, an officer used chemical spray, forcing Klein to move somewhere else, officials say.

Klein was arrested Thursday in Virginia and faces charges including obstructing Congress and assaulting officers using a dangerous weapon.

He was in custody on Friday and couldn’t be reached for comment. It was not immediately clear whether he had an attorney who could comment on his behalf. A Trump spokesman said he had no comment.

At least five people, including a Capitol Police officer, died as a result of the violence, and two other officers killed themselves after. More than 300 people have been charged with federal crimes.

Klein became a staff assistant in the State Department shortly after Trump's inauguration in 2017, according to a financial disclosure report. He held a top secret security clearance that was renewed in 2019, according to the court papers. He resigned from his position on Jan. 19, the day before Joe Biden was sworn in as president, authorities said.

One of Klein's State Department coworkers helped authorities identify him, officials said.

A Department of State diplomatic security special agent interviewed by an FBI agent said that Klein worked in the Office of Brazilian and Southern Cone Affairs, according to the court papers. The Department of State official identified Klein in photos and video shown by the FBI, officials said.