The nine-minute video from Eric Stillman's body camera showed the 34-year-old officer getting out of his squad auto and running after Adam Toledo in an alley at 2:30 am on March 29 in Little Village, a Mexican neighborhood on the city's West Side.
Claims that Adam had a gun in his right hand when he turned and faced the officer were later called inaccurate, WGN reported.
In the video, an officer gets out of his auto and begins chasing Adam down an alley. According to reports, the video shows that a firearm could briefly be seen in Toledo's right hand.
Toledo stops, turns and raises his hands. "You alright? Where were you shot?". Where you shot. Stay with me.
He calls for an ambulance and medical kit. Tensions were high on Thursday as a former suburban police officer in Minnesota appeared in court after she was charged in the killing last Sunday of a Black man during a traffic stop.
Another first responder on the scene later says, "Come on, little man, talk to me".
The Chicago Police Department has a long history of brutality and racism that has fomented mistrust among the city's many Black and Hispanic residents.
He can be heard imploring the boy to "stay awake" and, as other officers arrive, the officer who apparently fired the shot says he can't feel a heartbeat and begins administering CPR.
The video below contains graphic content and may be disturbing to some viewers.
And Lightfoot asked Chicagoans to remain calm and peaceful in the aftershocks of the tragedy.
In a statement released last week, the agency described it as "troubling video footage".
At a news conference on Thursday, Toledo family lawyer Adeena Weiss Ortiz said the boy was not holding a gun in the moment he was shot.
A still frame from the newly released body camera footage of the incident showed that Toledo wasn't holding anything and had his hands up when the officer shot him in the chest.
During a meeting with the mayor's office and attorney for the young boy's family, "both parties agree that all material should be released, including a slowed-down compilation of the events" that resulted in Adam's death.
In a news conference Thursday ahead of the video's release, Chicago Mayor Lori Lightfoot said she had seen the videos and they are "incredibly hard to watch".
"COPA's core values of integrity and transparency are essential to building public trust, particularly in incidents related to an officer-involved shooting, and we are unwavering in our commitment to uphold these values".
"There were a number of forces that met up at 2:30 in the morning on March 29 in an alley, and, simply put, we failed Adam", Chicago Mayor Lori Lightfoot told a news conference before the video was released.
But Chicago's mayor and police superintendent called for it to be released.
"It's sad to say that they're boarding up windows, blocking off entrances to business once again in anticipation of more rioting and looting", she wrote.