The District of Columbia's mayor says a police officer who fatally shot an unarmed black motorcyclist last year has been asked to resign.

Prosecutors said Wednesday that they won't file charges against the officer in the 2016 death of Terrence Sterling of Fort Washington, Maryland, because there was insufficient evidence to prove he used unreasonable force or wasn't acting in self-defense. City officials have acknowledged that the officer, Brian Trainer, violated policy by not activating his body camera until after the shooting, which happened following a high-speed chase.

Mayor Muriel Bowser said in a statement Wednesday evening that she doesn't "believe there can be real accountability if the officer remains on the force." Police are completing their own investigation, but Bowser says police have asked for his resignation.