So I'm still on Guiteau. He actually pled not guilty by reason of insanity. This was an early attempt at the insanity defense (and didn't work...). You can find out lots of trial details here. What I find interesting is Guiteau's "defense" itself:
I plead not guilty to the indictment and my defense is threefold: 1. Insanity, in that it was God's act and not mine. The Divine pressure on me to remove the president was so enormous that it destroyed my free agency, and therefore I am not legally responsible for my act. 2. The president died from malpractice ...if he had been well treated he would have recovered. 3. The president died in New Jersey, and, therefore, beyond the jurisdiction of this court.