Rex Dark said:
He was psychotic at the time of the attacks?
What about all the time it took to prepare them?
Probably just as insane.
People are confusing 'guilty' with 'he did it.'
Guilt requires two things in western law: actus rea and mens rea. Actus rea is the 'guilty action' and Mens rea is the 'guilty mind.'
Most successful defenses are based on actus rea: "He didn't do it." "He wasn't there." "You can't prove he was there." The insanity defense instead goes "He doesn't have a working brain."
Premeditation doesn't play into it; if his premeditation was under the 'crazy' than he's insane. "Temporary insanity" doesn't happen as often as you'd think, because "insanity" is rarely temporary. This would require a situation with such emotional and physical stress that the person is no longer cognizant.
A lot of the outrage comes from a misunderstanding of what legal insanity entails. Yes, you gotta be crazy to kill someone, but legal insanity is a specific, special sort of insanity where the individual truly is incapable of controlling their actions or being aware of what they're doing. Being driven to rage by anger, on the other hand, certainly is not legal insanity.