WASHINGTON (AP) — A man who worked as a U.S. State Department diplomatic security officer pleaded guilty on Friday to joining a mob’s attack on the U.S. Capitol over three years ago, court records show.

Kevin Michael Alstrup is scheduled to be sentenced on Feb. 12 by U.S. District Judge Randolph Moss.

Alstrup pleaded guilty to disorderly conduct and parading, demonstrating or picketing in a Capitol building. Both counts are misdemeanors carrying a maximum prison sentence of six months.

An attorney who represented Alstrup at his plea hearing didn’t immediately respond to an email seeking comment.

Alstrup admitted that he entered the Capitol building through the Senate Wing doors after other rioters had forced them open and broken windows aside them. He took photographs with a camera before leaving the building roughly 28 minutes after entering.

Alstrup was arrested in February in Washington, D.C., where he lived on Jan. 6. The judge allowed him to remain free until his sentencing.

The FBI determined that Alstrup, through his State Department work, “is familiar with providing security and protection for high-ranking government officials or sensitive locations, like embassies.” One of Alstrup’s supervisors identified him in a photograph of the riot, the FBI said.

At a press briefing on Friday, State Department spokesman Matthew Miller said that “we fully support the work by our colleagues at the Department of Justice to hold anyone responsible for violations of law on that horrific day accountable for those violations.” The department didn’t immediately respond to a request for more information about Alstrup’s employment.

Approximately 1,500 people have been charged with Capitol riot-related federal crimes. More than 900 of them have pleaded guilty. Over 200 others have been convicted by judges or juries after trials.

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Associated Press reporter Matt Lee in Washington contributed.