Christopher Knight, after 27 years of isolation from humans

Theft. While living in the woods he often stole food and such from homes in the area. But it appears he served less than a year in prison since, technically, he didn't hurt anyone. As far as I can tell with my research.

http://www.nbcnews.com/news/us-news/maine-hermit-christopher-knight-breaks-his-silence-n184956

For a long time, likely not. However, after so long he wouldn't have remembered anything other than isolation and would begin to be happy once more.

He sounds like someone with Schizoid Personality Disorder. They prefer solitude.