I rejected the argument years ago that Death Penalty is unjust for the mentally or emotionally challenged.
What is unjust is that ignoring the 99% of the mentally and emotionally challenged whose family work diligently to provide care and supervision to those unfortunates, and most of all the victims who are promptly forgotten, most inhumanely, the innocent second, third, fourth... victims.
At age 17 they cannot give a life sentence!
https://en.wikipedia.org/wiki/Life_imprisonment_in_the_United_States
In my opinion, Mental issues is all the more reason someone needs to be executed. As far as i'm concerned, "Insanity" ought to be an automatic Death sentence.