A white Chicago police officer has denied murder over the death of a black teenager who was shot 16 times in 2014.
Jason Van Dyke was heckled as he arrived at court where he denied six counts of first-degree murder.
Video released earlier this year showing the shooting of Laquan McDonald sparked an outcry and the resignation of the chief of police.
A federal investigation into the city's police is under way amid a national debate about the police use of force.
The inquiry will explore whether race plays a part in the police use of force and whether officers are properly held accountable.