http://www.sciam.com/article.cfm?id=...-chimpanzee-at
This happened in my state. Apparently the owner fed the chimp some Xanax and it went berserk.
The thing that intrigues me about this is that I've noticed a pattern with chimp attacks. Other great apes will bite and scratch your arms and legs, but chimps seem intent on disfiguring their victims. This isn't the first time a one has literally ripped someone's face off. I can't help but wonder if its active malice on their part rather than just an instinctive thing.