Officer charged with 1st-degree murder 'abused his authority' in firing 16 shots at a teenager

Officials in Chicago have released video that they say shows the shooting death of a teenager by a Chicago police officer last year. The officer is charged with first-degree murder and accused by prosecutors of firing 16 shots as the teen was walking away from the officer.

Laquan McDonald, 17, was killed in the October 20, 2014, shooting.

The video shows an encounter between several police officers - including Jason Van Dyke - who were responding to a call of a man with a knife.

In the footage, which does not include audio, McDonald is first seen jogging toward arriving police officers, then begins to walk away from them.

Moments later, McDonald is shot and collapses. At least one shot appears to hit him as he lies motionless on the ground.

The Chicago police union has said McDonald was "behaving erratically and refusing officers' commands" to drop a knife he was holding. The police union's statement maintains that Van Dyke "fired in fear for his life" and that McDonald "lunged" at Van Dyke with the knife.

The Chicago Tribune reports that Van Dyke, 37, fired 16 bullets at McDonald within six seconds of leaving his squad car and was reloading his weapon before another officer told him to hold his fire.

The police released the video in response to a court order that the footage be made public by Wednesday.

You can see the graphic video below. The final encounter begins around the 5:22 mark:

Cook County prosecutor Anita Alvarez said on Tuesday, "Clearly this officer went overboard and he abused his authority." She added, "I don't think use of force was necessary."

City officials in Chicago appear to have distanced themselves from Van Dyke and the police union.

During a news conference on Tuesday, Chicago Mayor Rahm Emanuel said, "Jason Van Dyke does not represent the police department."

Van Dyke is no longer on the police department's payroll, according to department officials.

Additional surveillance video allegedly deleted

Demonstrations continue in Chicago

Protesters have slammed the police union's claim that the shooting was justified. They are calling it an "execution."

Police shootings in the national spotlight

Demonstrations have spread across the country since Brown's killing as more black citizens, some of whom were unarmed, have been killed by the police, increasingly in encounters caught on video. In some cases, they died while in police custody.