To the best of my knowledge, Capote does not. Let us remember that Capote in this famous literary work was trying to write a kind of fiction non-fiction, if that does not seem to be a contradiction in terms. As a result, he merely reports the action of this famous murder case as it happened, and tries to do so in a detached narratorial voice. He does not jump ahead of himself and go to the end of the story, taking each event in order and attempting to present it in a manner that is as unbiased as possible.
At the same time, however, we need to remember that Capote published this book in the aftermath of the case and the execution of the two murderers, who had been dead for less than a year. It becomes clear therefore that it was read by a public who were already intimately familiar with the case because of the press attention it had received and already knew the ending. Therefore Capote did not need to reveal it to a readership that already knew how this text would turn out.