He has a choice. You maybe didn’t need to consciously make that particular choice but most probably you’ve had to make some other choices to be moral in life. It appears that most everyone has some tests to meet or work at—
When I was very young I was convinced that every murderer had to be "insane" to kill people. It is typically such a selfish act with such severe consequences for the murderer that I couldn't even imagine how anything other than insanity could explain it.
Since then I have learned to recognize that there is such a thing as "evil". Many, if not most, murderers are evil. But not all of them.
I think it quite likely that the Texas Tower shooter from years ago was not necessarily evil. After his death he was discovered at autopsy to have a significant brain tumor.
So, you tell me; was he evil? Was his a moral transgression?
I also don't believe that it takes a brain tumor to damage a brain. I think some people are simply born with damaged brains. We know that some environmental factors, like maternal drug abuse, can cause brain damage. I believe that poor genetic heritage can also result in having a brain that I would call "abnormal". I'm also convinced that a normal child can be mistreated in ways that lead to abnormal behavior.
From a practical perspective, we simply don't know enough to distinguish between immorality and brain damage in every case. I believe that there are plenty of each and that the public deserves to be protected from the risk of doing nothing to protect us from such persons.
We are at risk from the actions of evil people. We are also at risk from the actions of people whose brains are not normal. We are a long way from understanding whether this is two different things or just two points on a very broad spectrum. If it is a broad spectrum, then each of us lies somewhere along that spectrum, not necessarily at either limit.