19-year-old Arshell Dennis III was shot and killed in Chicago's Ashburn neighborhood hours from when he was to return to school to start his junior year at St. John's University. Today, hundreds gathered to say goodbye to a young man known as "Trey." Dennis was the son of a Chicago police officer. Dozens of CPD officers attended the funeral on the city's south side. The student was studying journalism and was remembered as funny, smart and thoughtful. Humorous anecdotes were mixed in with anger at how Dennis was murdered. Police say the investigation is being treated as a case of mistaken identity.