Aaron Mostofsky, 34, was reportedly "arrested by the FBI at his brother's residence in Brooklyn" and will appear before Eastern District Magistrate Judge Sanket Bulsara on Tuesday afternoon.
"I can confirm the arrest of Aaron Mostofsky by [an] FBI agent in New York this morning," FBI New York spokeswoman Adrienne Senatore told Fox News. "He is being charged by the USAO in D.C."
Mostofsky faces multiple charges for his role in Wednesday's siege, including the theft of government property, knowingly entering or remaining in a restricted building or grounds without lawful authority, knowingly, with intent to impede government business or official functions, engaging in disorderly conduct on capitol grounds, and unlawful entry and disorderly conduct.
The elder Mostofsky was elected to the Kings County Supreme Court last January, according to Gothamist.
Mostofsky's brother, Nachman Mostofsky, is the vice president of the South Brooklyn Conservative Club.
Attempts made by Fox News to reach out to Nachman were unsuccessful.
"I don’t think 75 million people voted for Trump — I think it was close to 85 million," he said. "I think certain states that have been red for a long time turned blue and were stolen, like New York."
The assault on the U.S. Capitol building resulted in the death of five people, including 42-year-old Capitol Police officer Brian D. Sicknick.