Remember the good ol’ days when a murderer was just a bad guy. No psychology was ever needed to figure him out. The James Cagney model.
We loved that model, because we weren’t bad guys. Bad guys were just certain types of people like certain types of dogs who would bite you while others would lick your nose. We were closer in personality to nose-lickers.
Today, we are more aware of the psychopathy behind homicide, and the embarrassed realization that we are all capable of being bad guys, and don’t all get that “Won’t you be my neighbor?” giddiness when there’s that dog next door.
Professor Albert Bandura, an innovative Canadian scholar in “social cognitive theory,” suggests that people who turn evil have justified the morality of their actions by disengaging from the brain’s more recently evolved control center for moral behavior. There are few outward signs to help identify these people and their unconscionable and crazy behavior. Maybe look for a fashion style fished out of a clearance bin. Or, youngsters turning to careers in insurance adjusting.