Muhammad Ali was one of the greatest boxers the world has ever known. Over a career spanning 21 years he became the heavyweight champion of the world an incredible three times. But on June 3, 2016 Muhammed Ali died after a long battle with Parkinson’s. But Parkinson’s is not fatal. So what killed him? Some believe Muhammad Ali fought for too long. Now, forensic pathologist Dr. Michael Hunter is reexamining the case to see what brought about the end of this one world-class athlete.