Steps to prove insanity
Mr. Dents had been following Uma Opee for several months and in reading his journal at the beginning one could mistake him for being completely sane. When his journal was read further it clearly had unstableness of mental illness written all of over it. The defense could hire a mental health expert or what attorney’s call upon the most in these types of situations, a psychiatrist, to conduct test. These tests will be evaluating and interviewing the defendants in the case also. We can also make sure that we are differentiating the mental illness from any other behavioral or psychiatric problems that Mr. Dents may have. We have to make sure the Mr. Dents did not understand his actions and those they were illegal. While proving diminished capacity we also have to apply the M’Naghten Rule to see if Mr. Dents knew right from wrong prior and during the events of the crime. We can even employ irresistible impulse test to give more credibility to the insanity defense. To gain a greater opportunity of proof of Mr. Dents mental health problems, the Model Penal Code Test as well. All of these step could very well lead Mr. Dents into a guilty but mentally ill verdict. This will then allow him to be found guilty but placed in a mental care facility instead or in exchange for time behind bars.

criminal.findlaw.com/...of-the-insanity-defense.html
Schmalleger, F., Hall, D. E., & Dolatowski, J.J. (2010). Criminal law today: An introduction with capstone cases. (4th ed.) Upper Saddle River, NJ: Prentice Hall.