Intent or Motive?

Different from many of the crimes we cover, we see homicide or murder has the additional dynamic of determining intent or motive in addition to the details of the crime of homicide or murder. (In criminal justice, proof of motive is not a necessity to prove murder, it is helpful but, as far as prosecution goes, not necessarily required to obtain a conviction.)

For this discussion, you will research and then discuss how or why we would not as a best practice investigate and even evaluate the psychological variables involved in all these cases versus the court order or defense- or prosecution-generated referrals?

Instructions
In your main post:

Compare and contrast what constitutes pathological and requiring evaluation versus understood and not requiring evaluation factors of this type of crime.
Discuss the possibility that it might be detrimental having a forensic professional involved in these type of cases. Why or why not?
Determine if the criminal justice system accounts for a crime that starts as domestic violence or assault and results in death differently from a crime when killing is the primary intent of the initial crime. Is your determination detrimental to the offender or to the protection of society?
Support your ideas with professional and scholarly resources.