Mayor Rahm Emanuel ousted Chicago's police superintendent on Tuesday, responding to an uproar over a white officer shooting a black teenager 16 times and anger at the Police Department for resisting, for more than a year, release of a video of the fatal shooting .
The video shows that Mr. McDonald, who was walking down a street holding a small folding knife, was several feet away from the officer and not moving toward him when the officer opened fire.
Mr. Emanuel was on the defensive throughout a news conference on Tuesday, his characteristic fiery manner kept in check as reporters suggested political motives for the city's moves - at one point, in response to a question, he said, "I just, if I could, beg to differ on that."
Critics of the police have suggested a cover-up, noting missing surveillance video from a Burger King near the shooting scene that might have shed light on what happened the night Mr. McDonald was killed.