Capote learned of the quadruple murder before the killers were captured, and he traveled to Kansas to write about the crime.

Considered by many to be the prototypical true crime novel,[2] it is also the second-best-selling book in the genre's history, behind Vincent Bugliosi's Helter Skelter (1974) about the Charles Manson murders.

[3] Some critics also consider Capote's work the original non-fiction novel, although other writers had already explored the genre, such as Rodolfo Walsh in Operación Masacre (1957).

In Cold Blood is regarded by critics as a pioneering work in the true-crime genre, although Capote was disappointed that the book failed to win the Pulitzer Prize.

They both pleaded temporary insanity at the trial, but local general practitioners evaluated the accused and pronounced them sane.

[citation needed] Hickock and Smith are also suspected of involvement in the Walker family murders, which is mentioned in the book, although this connection has not been proven.

[15] A defense motion that Smith and Hickock undergo comprehensive psychological testing was denied; instead, three local general practitioners were appointed to examine them to determine whether they were sane at the time of the crime.

[17] This opinion was not admitted in the trial, however, because under Kansas law the psychiatrist could only opine on the defendant's sanity at the time of the crime.

Aspects of these appeals were submitted three times to the United States Supreme Court, which refused to hear the case.

[19] After five years on death row at the Kansas State Penitentiary, Smith and Hickock were executed by hanging on April 14, 1965.

"[citation needed] The M'Naghten rules are used to determine whether or not a criminal was insane at the time of their crime and therefore incapable of being tried fairly.

He stated that "the M'Naghten rules ... are founded on an erroneous hypothesis that behavior is based exclusively on intellectual activity and capacity.

[27] He brought his childhood friend Nelle Harper Lee (who would later win the Pulitzer Prize for Fiction for her novel To Kill a Mockingbird) to help gain the confidence of the locals in Kansas.

[30] Capote later wrote a piece about following a cleaning woman, which he entitled "A Day's Work" and included in his book Music for Chameleons.

This is exactly what Capote did as he followed the court trials and interviewed those close to the Clutter family to create this story while it was unfolding in the real world.

However, some critics have questioned its veracity, arguing that Capote changed facts to suit the story, added scenes that never took place, and manufactured dialogue.

[7][31] Phillip K. Tompkins noted factual discrepancies in Esquire in 1966 after he traveled to Kansas and talked to some of the people whom Capote had interviewed.

The book made something like $6 million in 1960s money, and nobody wanted to discuss anything wrong with a moneymaker like that in the publishing business.His criticisms were quoted in Esquire, to which Capote replied, "Jack Olsen is just jealous.

[32]The prosecutor involved in the case, Duane West, claimed that the story lacked veracity because Capote failed to get the true hero right.

West had been a friend of Capote's while he was writing the book, and had been invited by him to New York City to see Hello, Dolly!, where he met Carol Channing after the show.

Their relationship soured when Capote's publisher attempted to get West to sign a non-compete agreement to prevent him from writing his own book about the murders.

[dubious – discuss] Alvin Dewey was the lead investigator portrayed in In Cold Blood, and stated that the scene in which he visits the Clutters' graves was Capote's invention.

The book depicts Dewey as being the brilliant investigator who cracks the Clutter murder case, but files recovered from the Kansas Bureau of Investigation show that Floyd Wells came forward of his own volition to name Hickock and Smith as likely suspects; furthermore, Dewey did not immediately act on the information, as the book portrays him doing, because he still believed that the murders were committed by locals who "had a grudge against Herb Clutter".

[37][38] The cover, which was designed by S. Neil Fujita, shows a hatpin with what appeared originally as a red drop of blood at its top end.

After Capote first saw the design, he requested that the drop be made a deeper shade of red to represent the passage of time since the incident.

"[40] In a controversial review of the novel, published in 1966 for The New Republic, Stanley Kauffmann, criticising Capote's writing style throughout the novel, states that Capote "demonstrates on almost every page that he is the most outrageously overrated stylist of our time" and later asserts that "the depth in this book is no deeper than its mine-shaft of factual detail; its height is rarely higher than that of good journalism and often falls below it.

"[41] Tom Wolfe wrote in his essay "Pornoviolence": "The book is neither a who-done-it nor a will-they-be-caught, since the answers to both questions are known from the outset ...

Instead, the book's suspense is based largely on a totally new idea in detective stories: the promise of gory details, and the withholding of them until the end.

[51] Capote's book was adapted by Benedict Fitzgerald into the two-part television miniseries In Cold Blood (1996), starring Anthony Edwards as Dick Hickock, Eric Roberts as Perry Smith, and Sam Neill as Alvin Dewey.