Agatha Christie up to the last chapter, then decided who the most unlikely suspect was, after which she would go back and make the necessary changes to "frame" that person. However, John Curran's "Agatha Christie: The Secret Notebooks" describes different working methods for every book in Christie's bibliography, contradicting the claim by Aldiss. Christie's mature novels, from 1940 onwards, often have titles drawn from literature. Four are from Shakespeare: Three are from the Bible: Another six are from other works of literature: In such cases, the original context of the title is usually printed as an epigraph. Similarly, the title of Christie's
Agatha Christie page of the paper on 6 August 1975. Following the great success of "Curtain", Christie gave permission for the release of "Sleeping Murder" sometime in 1976 but died in January 1976 before the book could be released. This may explain some of the inconsistencies compared to the rest of the Marple series—for example, Colonel Arthur Bantry, husband of Miss Marple's friend Dolly, is still alive and well in "Sleeping Murder" although he is noted as having died in books published earlier. It may be that Christie simply did not have time to revise the manuscript before she died. In 2013,