Well, JB. I just can not resist. 'Catalyst' is a psychological term...it just isn't as popular as 'dysfunctional'.
Attorneys have, for years tried to claim mental dysfunction to get their clients off. For years, the courts have not capitulated, except in a very few publicized cases, and have refused to recognize insanity as a defense.
IMO. This situation would be a wide open avenue for a creative writer whose main character was an attorney who wanted to use this defense, or a main character who commits murder and wants to get away with it.
Any psychological condition is never 'simple'.
Generally (and I emphasis GENERALLY!) Neurosis is a general term. Psychosis is a general term. GENERALLY...Neurosis are directed inwardly. GENERALLY...Psychosis are directed outwardly.
Imagine an outline. Psychosis is the heading. Listed under the heading, 'Psychosis ', are conditions: Sociopaths, Personality Disorders, etc. 'Neurosis' is the heading. Under this heading are conditions: split personality, depression, etc. There are definite divisions.
Can someone who is considered to 'normal' do murder? IMO, absolutely, if there is a 'catalyst' which negates/suspends/overrides their belief systems. Will they commit another murder? Probably not. But, who knows what their circumstances are and what they might do?
Can someone whose psychosis are 'hidden' commit murder? IMO, absolutely, if a particular set of circumstances ('catalyst') emerges. Will this person commit another murder? Who knows? Will the particular circumstances which encouraged the 'catalyst' occur again?
Are evil people (like Hanibal Lecter) psychopaths? Or is 'evil' a completely different catagory?
Your question has stirred up my creative mind, JB. HJL