The Insanity Defense is INSANE

If the State is going try an insanity case where Psychologists are performing mental evaluations, should there not be polygraphs & brain scans run to see if the "supposedly insane person" actually believes what they are saying? Instead, we have Psychologists that simply take the murderer at their word. The question should not be what they say, it should be....do they actually believe it. I think we would see many people proven NOT INSANE and NOT MENTALLY ILL. They are just EVIL.