Author P.D. James has a book about detective fiction with an excerpt here. She writes:
And why murder? The central mystery of a detective story need not indeed involve a violent death, but murder remains the unique crime and it carries an atavistic weight of repugnance, fascination and fear. Readers are likely to remain more interested in which of Aunt Ellie’s heirs laced her nightly cocoa with arsenic than in who stole her diamond necklace while she was safely holidaying in Bournemouth. Dorothy L. Sayers’s Gaudy Night doesn’t contain a murder, although there is an attempt at one, and the death at the heart of Frances Fyfield’s Blood from Stone is a spectacular and mysterious suicide. But, except in those novels of espionage which are primarily concerned with treachery, it remains rare for the central crime in an orthodox mystery to be other than the ultimate crime for which no human reparation can ever be made.


