actually if its a tactic to get a lighter sentence its a silly one. People who are found unfit to plead or stand trial can be placed in a secure facility without trial until they are no longer a danger to the public. if they are releasedits usually on a licence and are tightly monitored. additionally there is a known condition called folie a deux where a stronger character can foist their delusions onto a weaker one, causing the weaker one to become involved in the stronger one's activities.
as an aside, I wonder if that really is her given name?