The police and medical examiner need to believe that B's body is actually A's body, but it can't look like the hospital lost B's body. How can my ER doctor and a handful of accomplices pull this off?
1. Character (A) attempts to strangle a woman in a hospital parking garage. She fights back and he hits his head on the concrete.
2. A security guard arrives and calls for the hospital to send help. A is unconscious and either not breathing or struggling to breathe.
3. Staff rush A to the ER, but he dies within a few minutes from bleeding into the brain.
4. When police detectives/the Medical Examiner arrive, they are shown a different body (B) and told this is the man who died in the fight. The body is taken for autopsy and the investigation proceeds, only the ER doctor and a handful of other people can know the swap has happened.
About B - B is a homeless man of the same race as A, and around the same build, height and age. He hit his head when he fell down stairs while intoxicated or high. An ambulance crew take him to the hospital. He can die in the ambulance or just as he reaches the hospital. The ER doctor is the one to declare him dead.
Research so far - I've googled what deaths are investigated by the Medical Examiner's (ME) office in Chicago/Cook County. It appears that all accident victims are taken by the ME for autopsy. The hospital is supposed to report these deaths to the ME, but I can't figure out exactly how that plays out in practice. I'm guessing that B's accident and transportation is going to leave a trail (911 call, some kind of statement by EMS about where they took him) but I don't know what all the pieces of that trail would be, or how my bad guys can cover the trail so it doesn't lead to the hospital.