I can't remember the name of this movie. It involved a man who wrote a book about his killings and he then gave it to another and he copyrighted the book under his name as if he was the writer. The man that gave him the book was about to die, so he let him have it. Meanwhile the man never died.. he started being other characters in the movie such as a cop and a professor. Meanwhile, the book contained information about killing events that really occurred. Close to the end of the movie the man who was suppose to be dead killed his wife and planted her body in his cornfield. The cops never found out what happened.

The only movie I can think of that has a man burying his wife in a cornfield is Secret Window - the man is an author, there is an issue (kind of) of plagerism for one of his stories - but the rest of your description doesn't really match. Thought I would give it a try anyway...