I would posit that any time someone resorts to extreme behavior or acts of violence, that person is almost guaranteed to have some mental health issue going on. People in their right minds probably wouldn't do such a thing. BUT the problem becomes that now, this kind of behavior is what the public expects out of anybody with mental illness. "Oh, you have (insert diagnosis here)? Just like that guy in the news last month who.... (insert act of violence here.) I'd better stay away from you, because I might do something to set you off."

I also have problems with the notion that people with mental illness can't be held responsible for what they do. In my experience, no matter how (a relative, a friend, or a causal acquaintance) behaves, let them yell and scream and rage and curse and throw things all they want to. I am not supposed to be irritated or annoyed or hurt or angry in the slightest. If I do show that it bothers me, I get judged. "Shame on you. Can't you understand that he/she has a mental illness, and can't help it?" Where does it end?