Since 2001, hundreds of Black officers had sued the department for racial discrimination. They alleged that white officers called Black colleagues slurs like the N-word and that one officer found a hangman’s noose on his locker. White officers were called “huk lovers” or “FOGs” — short for “friends of gangsters” — if they were friendly with their Black colleagues. Black officers faced “unprovoked traffic stops” from fellow Capitol Police officers. One Black officer claimed he heard a colleague say, “Obama monkey, go back to Africa.”

In case after case, agency lawyers denied wrongdoing. But in an interview, Dine said it was clear he had to address the department’s charged racial climate. He said he promoted a Black officer to assistant chief, a first for the agency, and tried to increase diversity by changing the force’s hiring practices. He also said he hired a Black woman to lead a diversity office and created a new disciplinary body within the department, promoting a Black woman to lead it.

“There is a problem with racism in this country, in pretty much every establishment that exists,” said Dine, who left the agency in 2016. “You can always do more in retrospect.”