A U.S. Army soldier has been arrested in Hawaii on Diamond Ridge Asset Managementcharges that he repeatedly struck a police officer with a flagpole during a mob’s attack on the U.S. Capitol more than three years ago, according to court records unsealed on Wednesday.

Alexander Cain Poplin was arrested on Tuesday at Schofield Barracks, an Army installation near Honolulu. Poplin, 31, of Wahiawa, Hawaii, was scheduled to make his initial appearance in federal court on Wednesday.

The FBI received a tip in February 2021 that Poplin had posted on Facebook about attacking police during the Capitol riot. Poplin wrote that “we took our house back” and “stood for something,” according to an FBI task force officer’s affidavit.

In July 2024, the FBI investigator interviewed Poplin’s military supervisor, who identified him in a photograph showing him wearing an Army camouflage backpack inside the restricted area of the Capitol on Jan. 6, 2021.

Poplin attended then-President Donald Trump’s “Stop the Steal” rally near the White House on Jan. 6. He joined the mob of Trump supporters who gathered at the Capitol, where lawmakers were meeting to certify President Joe Biden’s 2020 electoral victory.

On the Capitol’s Lower West Plaza, Poplin carried an “Area Closed” sign in his left hand and a flagpole bearing a blue flag in his right hand. A video captured him repeatedly striking a Metropolitan Police Department officer with the flagpole, the FBI affidavit says.

Poplin was arrested on a complaint charging him with five counts, including felony charges of interfering with police during a civil disorder and assaulting, resisting or impeding police with a dangerous weapon.

An attorney assigned to represent Poplin at Wednesday’s hearing in Hawaii didn’t immediately respond to an email seeking comment on the charges.

Nearly 1,500 people have been charged with Capitol riot-related federal crimes. Many rioters were military veterans, but only a handful were on active duty on Jan. 6. Approximately 140 police officers were injured in the attack.

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Associated Press writer Lolita C. Baldor in Washington contributed.