A white Chicago police officer who shot a black teenager 16 occasions last year has been charged with very first-degree murder, state lawyers have stated.
Jason Van Dyke was not justified in shooting 17-year-old Laquan McDonald, state lawyer Anita Alvarez said.
A police dashcam video to be released on Wednesday is “chilling”, she added, and will “tear at the hearts”.
Police use of excessive force against African Americans has been the subject of nationwide protests for months.
In Minneapolis on Monday night, one particular of those protests was marred by violence when 3 white guys opened fire at a rally, injuring five men and women.
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In the Chicago case, a post-mortem showed that McDonald was shot at least twice in the back.
Ms Alvarez mentioned McDonald was carrying a knife when he was stopped by police in 2014 but was not threatening them or moving towards them.
Mr Van Dyke opened fire seconds right after he arrived and continued shooting at the teenager as he lay on the ground, he said.
“Whilst we expect officers to do their jobs… there are a couple of poor apples who go also far and break the law,” she said.
Chicago Mayor Rahm Emanuel has stated the officer was not justified in killing the teenager, calling his actions “hideous”.
“At each point, he violated what we entrust,” Mr Emanuel stated on Monday.
Illinois Governor Bruce Rauner has mentioned the video is “extremely troubling” and he expects a robust public reaction, though he hopes it will be “thoughtful and peaceful”.
The police union in Chicago has opposed the release of the video and mentioned it would taint a trial jury.
The officer, through his lawyer and the the police union, has stated he feared for his life because McDonald was holding a knife.
Chicago police have also stated McDonald threatened officers with a knife and slashed the tyres and windows of a patrol vehicle.