Several questions remain unanswered in a fatal Chicago police shooting case, a day after Mayor Rahm Emanuel fired the city's police superintendent.
Chicago, the third-largest city in the U.S., has been the site of several protests since police Officer Jason Van Dyke, who is white, was charged November 24 with first-degree murder in the October 2014 killing of black teenager Laquan McDonald.
Video from a squad-car dashboard camera, released last week, shows Van Dyke shooting McDonald 16 times in the middle of a street on October 20, 2014. Van Dyke, 37, continued firing at McDonald even after the 17-year-old had crumpled to the ground. Van Dyke's lawyer said he feared for his life before opening fire.
However, the video footage contradicts initial accounts police officials gave in 2014.
At the time, police said McDonald lunged at officers before shooting began, and a police statement just after the shooting said McDonald had refused to drop a knife and "continued to approach the officers."
Initial media reports based on police information also suggested McDonald was killed by a single shot to the chest.
However, the video shows McDonald walking down the middle of a four-lane street, and then appearing to veer away from police as Van Dyke opens fire.
The video shows something in McDonald's hand; a knife was found at the scene, with its blade folded into the handle.
Late Tuesday, Dean Angelo Sr., president of the Fraternal Order of Police Chicago Lodge 7, agreed McDonald did not appear to "lunge" at Van Dyke. But he added that McDonald did slightly "square his shoulders" toward Van Dyke, and said the police officer may have perceived that as a threat.
Van Dyke is not visible in the police video. He apparently was standing at least several meters away from McDonald when he shot the teenager.
Neither is it clear whether McDonald was walking toward the police at that moment, but from his reaction when hit by the gunfire -- he shuddered, turned slightly and fell to the ground -- it appeared he was not walking directly at the police.
Questions also are being raised about the lack of any sound on the police dashcam video. There also was no audio on any other videos taken from other police cruisers at the scene and subsequently released. Typically, police videos record sound as well as images.
Sound often gives insight to what's happening and why an officer or suspect acted the way they did, Ed Primeau, a Michigan-based audio and video forensics expert, told The Associated Press.
Chicago police spokesman Anthony Guglielmi suggested the absence of audio on the recording from Van Dyke's camera was most likely a technological glitch. However, he said it is hard to believe no audio was available on any of the police videos.
"It's a red flag," Guglielmi said. "I see it all the time -- not just by police, but by people trying to cover things up."
Activists accuse the city and police department officials of dragging their feet on the investigation and waiting over a year to release the video, and possibly even seeking to cover up what happened.
On Tuesday, Illinois Attorney General Lisa Madigan called on the U.S. Department of Justice's civil rights division to investigate Chicago police practices, including use of deadly force and the adequacy of its investigation of misconduct allegations.
The Justice Department could investigate the police force, as it did in Ferguson, Missouri, and Baltimore following deaths involving officers and unarmed black men in those cities.
The U.S. Attorney's Office said it has had an open criminal investigation into the shooting since April, which raises the possibility the federal officials are looking into authorities' handling of the incident beyond the initial shooting.
Mayor Emanuel announced Tuesday that he had asked Garry McCarthy, police superintendent since May 2011, to resign.
Emanuel also said he was creating a new police accountability task force to be advised by former Massachusetts Governor and Chicago native Deval Patrick.
The panel is due to provide recommendations by March 31 on how to boost independent oversight of police misconduct. The mayor said the task force also should ensure officers with repeated complaints are evaluated, and he called for releasing videos of police incidents in a more timely manner.
Emanuel formerly was chief of staff at the White House for President Obama, who calls Chicago his hometown.