I guess it depends on what "usually" means. Yes, there are people who are just trouble; it starts in kindergarden and doesn't ever stop until they end up in prison. Statistically, they are probably the largest group who are incarcerated because they are impulsive and often not very bright, and just plain don't seem to care a whole lot about outward appearances or following the rules. But there are plenty of people, numerous examples, in which people who have always seemed perfectly normal and have never been caught doing anything wrong just seem to up and murder someone. Take for example, Scott Peterson. It turns out he was a total wackadoodle, but his parents-in-law completely stood by him until evidence started to surface. Take this prison guard in NY who helped two convicted murderers escape with powertools and, oh, by the way, asked them to kill her husband when they were free, because one of them made her feel special. I don't recall reading anything about any sort of indication that she was murderous. And what about the man who killed Nancy Pfister? He had been a respected physician, no violent record, yes, he had some financial problems, but so do a lot of people. Plus everyone thought he was too physically impaired to kill anybody. I mean, so many people who kill have no criminal record. And aren't there more murders between people who know each other than there are random ones? That is the thing that is so frightening to me.
