According to the lawyers quoted in
this Guardian article, it seems that he would only need to show this kind of moral confusion
at the time of the act, and not be incapable of directing his own defence?
“If you are suffering from a substantial mental disease or defect, then it makes it unlikely that you could really appreciate the consequences of the acts, and that it was wrong based on your mental health at the time of the act.”
And according to a lawyer in New York, the 'extreme emotional disturbance' defence could be used, which, if successful, would bring down his sentence to 5-25 years:
“So what you’re left with is potentially a psych defense. Based solely on what’s out there, [it is] possible that extreme emotional disturbance was at play. Usually, these defenses are ‘something terrible happened, and somebody snaps’."
The lawyer thinks that the 'extreme emotional disturbance' defence would be Luigi's best chance.
[Edited to add italics.]
Lawyers weigh suspect’s options to fight charge he murdered UnitedHealthcare CEO Brian Thompson
www.theguardian.com