In Cold Blood by Truman Capote was published in 1966 and is often referenced as one of the first books of creative nonfiction. On a mid-November night in 1959, a family of four was murdered in their rural Kansas home by two men attempting robbery. In Cold Blood is the story of that tragic crime and its aftermath.
From the introduction and acknowledgments, readers know that Truman Capote conducted extensive interviews with police detectives, neighbouring residents, and the murderers themselves, once captured, to piece together the full story. Capote didn’t finish the book until after the trial and appeals of the murderers had been irrevocably settled.
Since the murderers are introduced in the book’s first few pages, In Cold Blood is not at all a whodunnit mystery. The reader knows the story will end with the capture of two criminals. How else could Capote have conducted his interviews with them and been able to write their narrative into the book from the beginning?
Although the story does follow Kansas police as they attempt to find the guilty parties, it is not really about solving the mystery of the crime since the reader is already in the know. Capote’s real story is about the psyches of the criminals. The author somehow succeeds in portraying these brutal murderers in a relatively sympathetic light as we follow them on the run and learn about their childhoods, insecurities, weaknesses, and dreams. Capote prompts the reader to ponder the nature of psychopathy, the morality of the death penalty, and the possible justifications for acquittal on the grounds of insanity.
If you're looking for to read something in the crime/mystery genre that goes beyond the basic "whodunnit" model and delves deeper into criminal psychology, I highly recommend you pick up a copy of In Cold Blood.