bomb, I never said he had a “mainstream” (to use your word) mental illness. I know very little about mental illness (of any kind) but I would think an murderer would fit the profile of someone who is mentally ill = mental illness. A person is naturally healthy or sick. There are different levels of sick, but someone sick is not a healthy person. This is just a matter of wording though.
(FYI, I read somewhere that he was in an accident as a child and since then there were some issues.)