About the book (from Wikipedia):
In Cold Blood is a non-fiction novel by American author Truman Capote, first published in 1966; it details the 1959 murders of four members of the Herbert Clutter family in the small farming community of Holcomb, Kansas.
When Capote learned of the quadruple murder, before the killers were captured, he decided to travel to Kansas and write about the crime. He was accompanied by his childhood friend and fellow author Harper Lee, and together they interviewed local residents and investigators assigned to the case and took thousands of pages of notes. The killers, Richard “Dick” Hickock and Perry Smith, were arrested six weeks after the murders and later executed by the state of Kansas. Capote ultimately spent six years working on the book. When finally published, In Cold Blood was an instant success, and today is the second-biggest-selling true crime book in publishing history, behind Vincent Bugliosi’s 1974 book Helter Skelter about the Charles Manson murders.
Some critics consider Capote’s work the original non-fiction novel, though other writers had already explored the genre, such as Rodolfo Walsh in Operación Masacre (1957). In Cold Blood has been lauded for its eloquent prose, extensive detail, and simultaneous triple narrative, which describes the lives of the murderers, the victims, and other members of the rural community in alternating sequences. The psychologies and backgrounds of Hickock and Smith are given special attention, as well as the complex relationship that existed between them during and after the murders. In Cold Blood is regarded by critics as a pioneering work in the true crime genre, though Capote was disappointed that the book failed to win the Pulitzer Prize. Parts of the book, including important details, differ from the real events.