The Madman Theory — Ellery Queen

Madman or murderer? That was the question and it was Police Inspector Omar Collins who had come up with the answer. All he had to go on was: the victim -- Earl Genneman, wealthy president of Genneman Labs; the scene -- right in the middle of a busy state park; the murder weapon -- a shotgun that was still missing; the witnesses -- Myron Retwig, Red Kershaw, Bob Vega, and Buck James, all friends or employees of the deceased; the motive -- unknown; the suspects -- everyone!