In a case study of criminalized behaviors, how do you define someone criminally insane?

I personally believe its concept invented by liberal lawyers to get their evil clients either time off their sentences, cushier surroundings for their imprisonment (the puzzle factory as opposed to general population where they will be raped and or murdered) or to get them off the death penalty, its one more way to pervert the course of justice in society that being to execute bad people who commit unspeakable if not evil acts then want to play the law game, its offensive to the victims/ families of the perpetrators and it makes the law system seem a joke when men gets 20 years for murdering someone then gets time off for good behavior and can come out in 10 years and still have the life to start over again, unfortunate that the victim in many cases does not have such a luxury.

Simplistically, I believe the answer to your question is involved with that person "knowing" what he did was "wrong". Or conversely, what he did was "not wrong". If he believes somehow that some other manifestation "made" him create such an act, angels, devils, society in general, than that is an argument, not easily made, that he may be unfit for trial and thus to be incarcerated in treatment for a very long time. I believe therein lies your bias judgment. Otherwise if he cops to the act or is caught by the facts of the act the payment is extracted but in more conventional incarceration or more extreme punishment. Society demands payment either way. It is just figuring out intent as in so many other things.