Video of Laquan McDonald's Killing Released as Chicago Braces for Protest

Chicago authorities pleaded for calm Tuesday as they released a "disturbing" dashcam video of the moment a cop shot Chicago 17-year-old Laquan McDonald 16 times last year.

Chicago police Officer Jason Van Dyke, 37, turned himself in Tuesday morning and was ordered held without bond on a charge of first-degree murder in the death of Laquan in October 2014.

"Anyone who is there to uphold the law cannot act as though they are above the law," Mayor Rahm Emanuel said at a news conference late Tuesday afternoon. "Jason Van Dyke does not represent the police department."