Although Leonski's crimes were committed on Australian soil, the trial was conducted under American military law. Leonski confessed to the crimes and was convicted and sentenced to death at a general court-martial on July 17, 1942. American General Douglas MacArthur confirmed the sentence on October 14, and a Board of Review upheld the findings and sentence on October 28. General Court-Martial Order 1 promulgated Leonski's death sentence on November 1. In a departure from normal procedure, on November 4, MacArthur personally signed the order of execution (in subsequent executions this administrative task was entrusted to MacArthur's Chief of Staff, Richard Sutherland). Leonski was hanged at Pentridge Prison on November 9.