the details have not come out. What we do know is that he was against the things that caused the fall of Enron. He reported early that Enron was up to no good, he was a whistle blower. It looks to me like the people he blew the whistle on got mad, and killed him and made it look like a suicide. Only a shrink would be able to tell you if he was depressed or not. His family would be able to tell as well. "Yes he was depressed and suicidal." the signs are almost always there.

Did he have anything to do with the fall of Enron? We don't know that either. But what we do know is that he left, because he knew they were up to no good. They apparently hid their debt, and lied to stockholders and the SEC. Now Enron and its execs are paying the price.