 Between 1939 and 1946, Leffingwell wrote 13 crime and mystery thrillers under his own name, as well as under his pseudonyms.His first novel, "Some Day I'll Kill You", introduced the radio ad man turned hard-boiled detective, Jim Steele, who would re-appear in a number of subsequent novels.Steele was referenced several times by the Holden Caulfield character in the novel "Catcher in the Rye" (Ch.