What was Capote's purpose for writing In Cold Blood?

Capote was fascinated with this case. Flipping through The New York Times on a November morning, he had come across a brief article outlining the murders with only the barest details (“Wealthy Farmer, 3 of Family Slain”), and imagined the case could be the subject of his next project, a long-form work of nonfiction. Check this out,

http://suite101.com/article/truman-capotes-purposes-for-writing-in-cold-blood-a378751