In the light of history it’s clear that however great Truman Capote’s literary gifts, his promotional genius surpassed them. The key theme in the publicity campaign he masterfully engineered for “In Cold Blood”—published as a four-part series in The New Yorker in the fall of 1965, and subsequently as a book—was that, despite having the stylistic and thematic attributes of great literature, the account of four brutal murders in Kansas was completely true. At the top of The New Yorker series was an “Editor’s Note” reading, “All quotations in this article are taken either from official records or from conversations, transcribed verbatim, between the author and the principals.” The book’s subtitle was A True Account of a Multiple Murder and Its Consequences. In interviews, Capote kept talking about the brilliant genre he’d concocted, the “nonfiction novel,” and colorfully described the methods he’d devised to insure his work’s veracity. A Times reporter drank it all in and wrote:

“To record real life, [Capote] trained himself for two years in remembering conversations without taking notes. Friends would read to him and he would try to transcribe what he had heard, eventually reaching the point where he was 92 percent accurate.’”...