Can you trust Truman Capote? In Cold Blood, true crime and what happens when murder becomes literature

A little while ago, I asked a question that probably isn't advisable for somebody who spends quite a lot of time writing about other people.

Can you ever really trust a writer? Rachel Cusk's Life of M got me thinking about it. Joan Didion provided the warning. And Truman Capote wandered briefly into the argument, having spectacularly demonstrated what can happen when a writer's friends discover that the funny little man at their dinner table has been paying considerably more attention than they realised.