p.s.
You could make the argument that Capote's Breakfast at Tiffany's, The Great Gatsby and O'Hara's Butterfield-8 are essentially companion pieces. If you read all three at the same time, it's difficult to tell which is the best told story.
OH Boy, I never knew that Capote wrote "Breakfast at Tiffany's" which I loved as a movie! BTW, you are right about the true crime novels, but I thought he sympathized a bit too much with the criminals rather than the family they slaughtered.
It's been years since I read it (in high school) but I also remember being repelled by his graphic descriptions of the kid's murders. Seemed to take too much enjoyment in it.