The death was never fully explained and no-one was ever arrested for Cooper's death.[17] His injuries were consistent with buckshot wounds from the type of shotguns the Detroit Police Department used at that time.[18] In their testimony about the entering of the annex, Guardsmen, State Troopers and Detroit police officers all testified they were not the first to enter, stating that Cooper was already dead when they arrived, leaving responsibility for the death unexplained.