"I watched him take his last breaths, just a reflex breath. And I remember as I watched him breathe out the last part of air, I thought: Is this the best thing I've ever done, or the worst thing I've ever done? This is real and that's him. Holy sh**. His forehead was gruesome. It was split open in the shape of a V. I could see his brains spilling out over his face. The American public doesn't want to know what that looks like."
ADDED: Here's the long Esquire article.