Chicago police released hundreds of pages of reports late Friday about the shooting death of a black teenager by a white police officer.

Several officers, including Jason Van Dyke who is charged with murder in the shooting death of 17-year-old Laquan McDonald, reported that the teen approached officers while armed with a knife. However, footage from the police car’s dashboard camera appear to show McDonald veering away from the officers down a four-lane street in October 2014 before he was shot 16 times.

The video shows Van Dyke opening fire from close range and continuing to fire after McDonald fell to the ground.

Van Dyke told an investigator that McDonald was “swinging the knife in an aggressive, exaggerated manner.” And that McDonald “raised the knife across chest” and pointed it at Van Dyke, according to one police report. Another report describes how Van Dyke feared for his life.

"In defense of his life, Van Dyke backpedaled and fired his handgun at McDonald, to stop the attack," one document reads. "McDonald fell to the ground but continued to move and continued to grasp the knife, refusing to let go of it."

Details of the October night emerged in hundreds of pages of handwritten and typed reports that prompted supervisors to rule McDonald’s death a justifiable homicide hours after he was shot.

The Cook County state's attorney's office charged Van Dyke last month, the same day the city released video of the shooting. City officials had fought in court for months to keep the video from public release, before deciding in November not to fight a judge's order.

The release of the footage triggered protests and calls for public officials, including Mayor Rahm Emanuel, to resign. Illinois Attorney General Lisa Madigan has called for an overall federal probe of police department practices, which top Democratic presidential candidates to local Illinois politicians have echoed. Emanuel has since fired the police chief, expanded a body camera program and formed a task force.

Chicago police spokesman Anthony Guglielmi said the Independent Police Review Authority conducts all investigations of officer-involved shootings and the agency was given the case report and videos. He said that the U.S. Department of Justice's investigation was also ongoing.

"If the criminal investigation concludes that any officer participated in any wrongdoing, we will take swift action," he said in an emailed statement.

Despite Van Dyke’s account of the shooting, he has a history of civilian complaints against him stemming from allegations of excessive force.

As recent as Dec. 1, 2013, Van Dyke was accused of directing racial slurs at a woman as police search her apartment, according to The Associated Press, citing records from the Independent Police Review Board. The board eventually concluded the woman was “invasive, disruptive and provocative such that her arrest also would’ve been justified had it occurred.” The board concluded the officers’ actions were justified.

The Associated Press contributed to this report.