A former Houston police officer has turned himself in for allegedly participating in the U.S. Capitol riot on Jan. 6.

The 18-year veteran, Tam Dinh Pham, has been charged with knowingly entering a restricted government building and engaging in disruptive and disorderly conduct, The Texas Tribune reports. Houston Police Chief Art Acevedo informed investigators about Pham attending the insurrection after seeing Facebook photos linking Pham to the event.

Pham eventually met with FBI agents, and told them that he traveled from Houston to D.C. on Jan. 5 to join his wife on a business trip. While admitting that he attended Trump’s "Stop the Steal" rally earlier that day, he denied ever entering the Capitol. But that didn't hold water after investigators found photos of Pham in the Capitol rotunda in the deleted photos section on his phone. He agreed to comply with the investigation only after being warned about lying to the FBI.

Pham said his goal wasn't to riot, but to “see history,” and told agents that out of the 15 minutes in which he was inside the building, “he looked at the historical art on the walls and took photographs and videos inside.”

Acevedo announced last Thursday that Pham had resigned from the police force. “We are also auditing arrests made by this former officer to ensure there are no irregularities, to include the review of his body worn camera footage related to his arrests,” he said in a statement. “While our community and members of our department are understandably upset about this breach of trust, all should be heartened by our swift, decisive, and transparent action.”

That Pham was a police officer isn't some kind of outlier, either. According to analysis from NPR, 1 in 5 of the people charged in the riot served in the U.S. military.