The Appellate Court here found the evidence to be rather extensive that the Defendant knew that the man he was beating in the head with a baseball bat was a police officer and that this Officer suffered great bodily harm based on the extent of his injuries, which included bleeding from the head and four months of physical therapy.
The case is People v. Tythia Thigpen.
http://www.illinoiscourts.gov/Opinions/AppellateCourt/2017/1stDistrict/1153151.pdf