The Chicago Sun-Times reports that investigators from the department's special victims unit began investigating the clip after a well-known local community activist was shown the video by a woman on the street who was upset about it. The activist, Andrew Holmes, them passed it on to the cops.
The version above was edited by the Sun-Times to hide the child's face.
The video shows a child wearing a diaper while smoking as a man is heard off-camera encouraging him to "smoke bro, inhale it." Before the clip ends, the man says, "Let me hit that, OK?"
Holmes told the newspaper that the woman said she came across the video while browsing Facebook, but had no idea where it came from or who the man or the child are.
If you recognize anyone in the video, contact the Chicago Police Department.