Capote wrote In Cold Blood as a literary experiment. He wanted to write a "nonfiction novel." He felt that he was one of the rare creative people who actually took journalism seriously. The question is whether a book such as In Cold Blood is actually a novel, a creative work, or journalism.
We can pinpoint several artistic aspects of In Cold Blood. First, Capote has to make choices about the structure of the book. Capote chose a starting and ending point, and in between he choose the order and subject matter of the chapters. In the first section, "The Last to See Them Alive," chapters on the activities of the Clutter family alternate with chapters on the preparations for murder being made by Hickock and Smith. Reading about Nancy Clutter baking a pie and then reading about the killers' tattoos creates a montage, contrasting subsequent images to create a specific impression. No newspaper article would have such a creative structure.
When In Cold Blood was first published in January 1966, Hickock and Smith had been dead for less than a year. The murder and trial had garnered big headlines, and many readers probably knew the details of the novel before they began reading it. Capote had to make it interesting even to people who knew the outcome--the book had to be good literature as well as be informative and accurate. The novel is saturated with details that would never have been included in a newspaper. Moreover, the details are carefully picked. Knowing that Capote compiled 8,000 pages of research, the book seems to be a very carefully edited selection of facts and descriptions. For example, very little is said about the two older Clutter daughters, although Capote doubtless interviewed them. He left them out for artistic reasons. This shows that the facts of the Clutter case were the building blocks for what was ultimately a creative work.
In arranging the facts of the Clutter case into a novel, Capote gave them a number of meanings. Not only are some of Capote's opinions apparent--as in the case of his opposition to the death penalty--but the novel itself has several major themes. First, it is a commentary on the American Dream. Herb Clutter has made a wonderful life for himself--his daughter, after all, bakes pies. But Herb Clutter's American idyll is abruptly and arbitrarily shattered by two petty criminals. The American dream is fragile, and it only functions if marginal people (ex-cons) are not present.