In hundreds of pages of newly released Chicago police reports, some officers described McDonald aggressively coming at Officer Jason Van Dyke -- now charged with first-degree murder -- while waving the knife and ignoring orders to drop the weapon.
In accounts at odds with video of the incident, some officers said McDonald fell to the ground after Van Dyke fired his weapon but continued moving and attempting to get up with the knife still in his hand. One officer said he believed McDonald was attacking the officers and "attempting to kill them" when Van Dyke opened fire.
Van Dyke had been on site less than 30 seconds, and out of his car for six seconds, when he started shooting, Cook County State's Attorney Anita Alvarez has said.
Van Dyke told investigators that McDonald was "swinging the knife in an aggressive, exaggerated manner" and raising the weapon above his shoulder from about 10 to 15 feet away, according to the reports.
One handwritten report, referring to Van Dyke by his initials and McDonald as the offender, said: "VD believed O [offender] was attacking with knife ... trying to kill VD ... In defense of his life VD backpedaled + fired ... O fell to the ground, continued to move/grasp the knife ... VD continued firing. O appeared to be attempting to get up, still holding the knife, pointing at VD."
In one report, Van Dyke is quoted as saying that from his training he knew that an assailant with a knife posed a deadly threat, possibly hurling the weapon at the officer. Van Dyke also referred to a Chicago Police Department bulletin warning officers of a knife capable of firing a bullet. A copy of the bulletin was included in the report.
The Chicago Police Department said the Independent Police Review Authority is conducting the investigation into McDonald's killing.
"If the criminal investigation concludes that any officer participated in any wrongdoing, we will take swift action," police spokesman Anthony Guglielmi said in a statement.
Meanwhile, the Justice Department plans to announce a pattern-and-practice investigation of the Chicago Police Department, a person familiar with the matter confirmed to CNN, expanding the ongoing civil rights probe of McDonald's death.
Video of another police shooting
With aftershocks from the release of dashcam video showing McDonald's shooting still rumbling through Chicago, a dashcam video of yet another fatal police shooting is about to be released.
Mayor Rahm Emanuel said Thursday the city will release video showing the death of Ronald Johnson, 25, more than a year ago, according to CNN affiliate WLS-TV
There was no indication from city officials on when the video would be made public.
But Emanuel's announcement came a week before U.S. District Judge Edmond Chang is scheduled to decide Thursday whether to compel the city to release the dashcam video.
Johnson was shot and killed by Officer George Hernandez in October 2014.
According to a preliminary police statement released the same day as the shooting, Johnson pointed a weapon at pursuing officers, after first attempting to flee on foot.
Johnson's family does not believe the official account.
'Y'all covering up this murder'
Johnson's mother, Dorothy Holmes, says the dashcam footage of the shooting proves her son was slain and is pushing for the video's release to the public.
"Y'all covering up this murder. It's been over a year now that my son been murdered and y'all still haven't did y'all job to convict this cop of murder. Shouldn't nobody have to go through this pain over their kids," Holmes told reporters Tuesday.
Johnson's case -- and the video -- is receiving renewed attention in the wake of the case of McDonald, a black teenager.
McDonald, was shot and killed by a Chicago officer in October last year, eight days after Johnson. Dashcam video of that shooting was recently released after a judge ordered it be made public, sparking outrage and protests.
13 months to release video
The fallout from McDonald's death -- and the fact that it took 13 months for the police department to release the video of the shooting -- has rocked Chicago and led to Chicago Police Superintendent Garry McCarthy's resignation.
Many people who took to the streets questioned why it took so long to release the video.
In the Johnson case, family attorney Michael D. Oppenheimer told reporters in the wake of Emanuel's announcement he "wasn't that surprised, given the pressure we've put on them, the press has put on them, that the public has put on them.
Cook County State's Attorney Anita Alvarez's office will investigate the possibility of criminal charges against the officer, her office said Wednesday.