In 1972, Morrell sold the film rights to "First Blood" to Columbia Pictures, who in turn sold them to Warner Bros. The film languished in development hell for ten years, with the story passing through three companies and eighteen screenplays. Finally, Andrew G. Vajna and Mario Kassar, two film distributors looking to become producers, obtained the film rights. Sylvester Stallone was cast in the lead role, due to the star power he had from the films "Rocky" and "Rocky II". Stallone was able to use his clout to force changes to the script to make Rambo a more sympathetic character, including having Rambo not directly kill any police or national guardsmen (in the novel, he kills many), and having him survive at the end instead of dying as he does in the book.