Very good point you made here Pachy. Although some violent cases like this might have some mental illness component, many don't. I heard a specialist (FBI agent) who said something important. The common factor in a tragedy like this is, the person has reached the point where they've lost all empathy ....... where they can't turn back. This can happen to a person who's not mentally ill. The great majority of mentally ill people won't commit an atrocity like this. Its the person who's reached the end and doesn't see the victims as humans or have any feeling for them.