ROBERT SIEGEL, HOST:
It has been four days since Stephen Paddock fired out of the 32nd floor of the Mandalay Bay hotel. And as for his motive - we have no idea. What if we never have an idea of what made him do it? For a sense of how unusual that would be, we reached out to Mark Follman. He maintains a database of mass shootings in the U.S. going back to 1982, and he has spent years profiling mass shooters for the magazine Mother Jones.
Mark, welcome back to the program.
MARK FOLLMAN: Good to be with you, Robert.
SIEGEL: Let's assume that we never gain a clearer idea of Stephen Paddock's motive. Would he stand out in your database? Or would there be many others who were similarly opaque as to what was going on inside their minds?
FOLLMAN: Oh, I think in most cases it can be fairly inscrutable what they were really thinking, what really motivated them to do something so horrific and unusual. In some cases, you do have clear indications of a motive. You can look at the case in Charleston, S.C., a few years ago with Dylann Roof, who declared very explicitly a racial motive to attack. But even that doesn't really fully explain why he did what he did.
SIEGEL: Can you think of a case in which somebody who's - who has experienced no dramatic change or nothing terrible either in a personal relationship, financial relationship, spiritual relationship, physical or mental health suddenly turns out to indiscriminately kill people? Or does that strike you as anomalous?
FOLLMAN: Well, it seems unlikely. And my hunch is that the more investigators look into this case, the more that they will learn about the life circumstances of this person, the mental health condition, the behavioral condition and things that might have set him off on an idea that he was developing and then planning to commit this attack. In the evolving field of threat assessment, which is mental health and law enforcement professionals working together to try to understand and prevent these kinds of attacks, they're looking at a process that they refer to as the pathway to violence where a person develops this idea, plans it and then carries it out.
And often it's a person who's got some very serious problems in their life. And there may be something that happens that then sets them off. They refer to this as a triggering event. And this speaks to, I think, another public misconception about this problem. You often hear all this talk about, well, what made him snap...
SIEGEL: Yeah. Yeah.
FOLLMAN: ...As if it was an impulsive act. But these are not impulsive crimes. They're planned crimes and often carried out very deliberately, which you can see in the case in Las Vegas.
SIEGEL: If we look at Stephen Paddock's history and the story of his life, perhaps the most unusual thing about it is that his father was a bank robber who made it to the FBI's Ten Most Wanted list. Can you imagine somebody harboring a trauma from decades and decades ago or some predilection toward crime or violence that he might have?
FOLLMAN: It's an interesting data point, isn't it? One of the forensic psychologists - a threat assessment expert I spoke to talked about how the father, who was classified as a psychopath - a dangerous psychopath - by the FBI in 1969, that is a heritable trait. And it's possible that Paddock had psychopathic characteristics. That wouldn't explain the specific act he committed, but it could begin to explain the - his disposition and the capability he might have had, the kind of detachment and cruelty and lack of empathy that might allow him to develop a thought process and a planning process to go out and commit an attack like this. We may never really know any answers of that nature. And that's part of the reason why the question of motive is so difficult with these cases.
SIEGEL: Mark Follman maintains a database of U.S. mass shootings for Mother Jones, where he's national affairs editor. Mark Follman, thanks for talking with us once again.
FOLLMAN: It's good to be with you. A tough week, and my heart goes out to all the people in Las Vegas, but thank you for having me. Transcript provided by NPR, Copyright NPR.