Watch | Chicago releases video of cop fatally shooting black teen

A white Chicago police officer who shot a black teenager 16 times last year was charged with first-degree murder on Tuesday, hours before the city released a video of the killing that many people fear could spark unrest.A judge ordered that the recording be put out by Wednesday. Moments before the footage was made public Tuesday evening, the mayor and the police chief appealed for calm.City officials spent months arguing that the footage could not be made public until the conclusion of several investigations. After the judge's order, the investigation was quickly wrapped up and a charge announced.Some community leaders said there was no doubt that Alvarez only brought charges because of the order to release the video from Oct. 20, 2014 that shows the shooting of 17-year-old Laquan McDonald.