Thanks for this thoughtful and well considered reply. I confess that the frustration of feeling that we cannot know what we need to know to prevent these tragedies gets to me.
Professor Katherine Ramsland, who has studied serial killers as much as anyone in the world, says she can't do it. In
an interview with The New York Times, she disputed claims that people who knew the so-called BTK killer should have been able to recognize his evil:
"When I mentioned my thoughts to Ramsland, though, she disagreed that people who knew Rader could have connected the dots. Why would they? To the contrary, one reason Ramsland believes that Rader was able to keep his cover was that 'he grew up in a Germanic Midwestern family where there was not a lot of emotion. Like my family.'"
In her book about BTK - “Confession” - she posits "that some serial killers are more like the rest of us than common wisdom tells us. In the annals of serial killers, [BTK] is hardly the only one who held down a facade of normalcy while hunting his prey, but he managed it far longer than many others. There are many qualities, Ramsland writes, that ordinary people share with so-called monsters: 'overestimating our willpower, idealizing ourselves, daydreaming about power, indulging in secret behaviors that keep attracting us, deceiving others and keeping secrets.'"
I am confident that I won't kill anyone, but not because I'm not capable of it. I grew up in a religious family, and as I watch my kids grow I have come to appreciate what the discipline of a religion based upon a creator-god of infinite love, whose only command is that we accept and share that love, does to civilize us, to create and enforce family and community standards of good behavior, and thus to curb the animal behavior that would otherwise manifest itself more often among us.
There are other disciplines that have the same effect, of course; moral and ethical standards are built into many professional disciplines and unionized work communities. But IMO it is the discipline imposed by culture and its institutions and communities that keeps humans from killing and maiming each other when they're very angry.