I certainly sympathize with the idea that one "must have to be insane" to do something like this. By the same token, statements and letters made by these folks, while they seem dramatically misguided and evil, don't seem to be lacking thought, rational faculty, or consideration. Was the guy aware of what he was doing? Did he consciously make the decision to do it? Did he know that it would result in death? Was he aware it was wrong? If all of those are true, I don't think he was insane. I think sometimes people choose, with their full faculties, to perform evil. And evil does exist in the world. I suppose it's easier to think they just went batty.