Kansas City police received a postcard dated June 30, 1933 from Springfield, Missouri which read: "Dear Sirs - I - Charles Floyd - want it made known that I did not participate in the massacre of officers at Kansas City. Charles Floyd". The police department believed the note to be genuine. Floyd also reportedly denied involvement in the massacre to the FBI agents who had fatally wounded him. In addition, a recent book on the massacre attributes at least some of the killing to friendly fire by a lawman who was unfamiliar with his weapon, based on ballistic tests.