The Honeymoon Killers (1969) is the result of Leonard Kastle's reaction to Bonnie & Clyde. Have you seen pictures of the real Clyde Barrow and Bonnie Parker? These were not beautiful people. They certainly looked nothing like Warren Beatty or Faye Dunaway. Kastle wanted to craft a crime movie that avoided ties to Hollywood glamour. So he researched one of the most infamous crime cases of the '40s: the "Lonely Hearts" murders.