Looking within the mind of a rampage killer

This report was originally broadcast on February 20, 2013.

MAN: There you go, that's it.

MAN: Andy was always real playful.

MAN: There you go. Take the turn.

MAN: He was a real kind kid.

MAN: Hi, Megan. Hi, Andy.

BOY: Hi, daddy.

MILES O'BRIEN: How did the sweet kid in the home movies become the murder suspect on the 6:00 news?

REPORTER: As you said, mostly students and parents meeting up with one another, and I'm sure so shocked that they just want to see which other friends are out there.

MILES O'BRIEN: What made Andy Williams, then 15, walk into a boys room at Santana High School in Santee, Calif., and open fire on his schoolmates, killing two and injuring 13?

JEFF WILLIAMS, Father of Andy Williams: See, this one I think is eighth grade.

MILES O'BRIEN: His father, Jeff, is haunted by the question.

So, he wasn't a kid that was infatuated with violence?

JEFF WILLIAMS: No, not at all. You have the silly clown. That's the thing. You don't expect the silly clown to do something like this, to go kill people.

MILES O'BRIEN: The class clown.

JEFF WILLIAMS: The class clown would be the class killer.

MILES O'BRIEN: The mind of a rampage killer can live behind the face of the boy next door. Can science shed any light in these darkest of dark places? There is not much data to go on. From Columbine through Newtown, in most cases, the shooter ends up dead, either by his own hand or by police.

But Andy Williams is one of the few living school rampage shooters.

AUTOMATED CALL RECORDING: This recorded call is from an inmate at a California correctional facility.

MILES O'BRIEN: He called me collect from a pay phone inside the Ironwood Prison in the middle of the Southern California desert. Andy Williams is now 27. He has spent 12 years behind bars.

Take us back to that moment, and if you can tell us what was going on in your mind at the time, that would really help us.

ANDY WILLIAMS, Convicted Murderer: To me, it was just like a numbness at the time. You know what I mean? And like I couldn't really — like, at 15, I didn't really think, like, all that stuff through. I didn't think two boys were going to die. I didn't think 13 people were going to get shot. I just thought I was going to make a lot of noise and that the — and that the cops were going to show up.

JEFF WILLIAMS: This is the county all-star team he was on for baseball.

MILES O'BRIEN: He was a good baseball player, huh?

Andy had moved from Maryland with his dad after his parents had divorced. He was the new kid at school, and even the boys that accepted him bullied him unmercifully.

So, he was really going through hell?

JEFF WILLIAMS: The new kid at this big school and being tormented by the older kids there.

MAN: We're getting buzzed off of it.

MILES O'BRIEN: Andy started drinking, smoking pot and taking prescription painkillers, and he had access to a gun. He had boasted to his friends that he was planning the rampage.

It is a volatile mix, but, sadly, a common one. So what separates a rampage killer from other struggling teens? Is it genetics or something in their environment?

Josh Buckholtz is a Harvard neuroscientist searching for the biological roots of violent behavior.

JOSH BUCKHOLTZ, Harvard University: One of the most infuriating things as a scientist and as a person is this attempt to try and find some diagnostic label, some neat diagnostic box to put this person into and — and thus explain why they did this terrible, terrible thing.

MILES O'BRIEN: But as researchers peer into the brains of criminals using MRIs, they are finding some faulty wiring.

One of these circuits connects the prefrontal cortex, responsible for higher-level thinking, to the amygdala, an emotion center, which goes into overdrive whenever a threat is perceived. If the threat is not real, the prefrontal cortex will send a message to the amygdala to calm down. But if the wiring is faulty, that calming message may not get through.

JOSH BUCKHOLTZ: In those folks, it seems like this circuit is broken in such a way that they're more likely to respond with greater amygdala activity and greater emotional arousal when they think that they're being faced with some kind of threat.

MILES O'BRIEN: Even in perfectly healthy brains, the prefrontal cortex is not fully developed in the teenage years, but the amygdala is. This is one reason why teens tend to have bigger emotional swings. Now imagine a teen with the early stages of mental illness.

KATHERINE NEWMAN, Johns Hopkins University: They are people whose mental conditions often cause them to amplify to the sort of social slights that happen all the time in high school.

MILES O'BRIEN: Katherine Newman is a sociologist at Johns Hopkins University and author of "Rampage: The Social Roots of School Shootings."

KATHERINE NEWMAN: So, these are kids who are desperate to be accepted. They are not loners. They are people who are trying to join groups all of the time, but their experience every day is friction. It never works.

MILES O'BRIEN: Did you feel suicidal?

ANDY WILLIAMS: Absolutely. It was like an eight-month constant, like — like I wonder if things would be better if, if I wasn't — if I wasn't like in this city, in this state, like, or even on this Earth. So my grand scheme, like my grand plan was suicide by cop.

MILES O'BRIEN: Andy planned a so-called suicide by cop, expecting the authorities to gun him down, but he had a change of heart at the last minute, dropped the revolver and surrendered.

Researchers say 60 percent of rampage shooters are suicidal before the carnage. Psychologist John Keilp studies suicidal people, trying to find out how their brains differ from others.

JOHN KEILP, Columbia University: We're looking at what's different about those people. And one of the things I think we feel confident about is that there is something different about those people, that it's not just a feature of depression.

Just take your three fingers, put it on the buttons, and one, two, and three stand for the response red, blue or green.

MILES O'BRIEN: Keilp believes one fundamental difference may show up in a deceptively simple test, which he let me try.

JOHN KEILP: Goes through the set as quickly as you can.

MILES O'BRIEN: It is called a Stroop test invented by psychologist John Ridley Stroop in the 1930s. It sounds simple– all I had to do is identify the color I saw in the screen.

MILES O'BRIEN: Gosh, this is harder than you would think.

JOHN KEILP: They notice right away how you slow down.

MILES O'BRIEN: Yes. Oh, yes. I don't know why this is — this shouldn't be that hard. Why is that?

JOHN KEILP: Well, that was Stroop's big discovery.

MILES O'BRIEN: Keilp had two groups of people complete Stroop tests while their brains were in an MRI.

JOHN KEILP: And it's just lie still and relax, OK?

MILES O'BRIEN: One group was depressed. Some had attempted suicide, and the other was healthy. He noticed a surprising difference in their brain scans. These are healthy brains doing a Stroop test when the color and the word don't match.

The red areas denote increased blood flow, and thus brain activity, in the frontal cortex region, the cingulate, which resolves conflicting perceptions, and the visual regions as well. Now look at the brains of depressed, suicidal people doing the same test.

That's very dramatic.

Keilp says their brains seem inclined to focus on one thing, in this case the word, not the color, and are less flexible. It may mean their brains are wired in a way that makes them fixate on suicidal thoughts. Research like this may take scientists closer to a means of screening for suicidal tendencies, especially in adolescents who would never admit to it, like Andy Williams.

But the question remains, why does someone who wants to end his own life decide to take so many others with him?

KATHERINE NEWMAN: You are looking for a way to change this terrible social reputation you have as a loser, and you land on the idea of shooting people after many other failed attempts to change your social reputation.

HEATH LEDGER, "The Dark Knight": Good evening, ladies and gentlemen.

MILES O'BRIEN: Often, rampage shooters cast themselves as a Hollywood villain, the antihero. The shooter who opened fire in a movie theater in Aurora, Colo. was infatuated with the Joker in the Batman movies.

KATHERINE NEWMAN: The antihero is a respected character, respected through fear. And that feels a lot better to them than dismissed, belittled, insignificant.

MILES O'BRIEN: Better to be infamous than irrelevant?

KATHERINE NEWMAN: Better to be infamous than invisible.

MILES O'BRIEN: Jeff Williams says he had no idea a rampage killer was living under his roof.

So, why were you holding back from your father, though?

ANDY WILLIAMS: I don't know, man. I think I was like — I was just ashamed to confront, like, my failure.

MILES O'BRIEN: Do you love your son?

JEFF WILLIAMS: Yes, I love my son very much. I do not condone what he did. I do not condone the way he went about trying to resolve his issues whatsoever. He made a very bad choice. I can't change that.

MILES O'BRIEN: Research may never give us an easy way to identify a future rampage killer, but it has proven the roots of a rampage run deep. And there are many ingredients in the mix long before the carnage. If only we were better at seeing the signs of trouble.

JUDY WOODRUFF: NOVA's "Mind of a Rampage Killer" premieres tonight at 9:00 p.m. Eastern time. Check your local PBS listing for details.

And, online, you can listen to Miles' full interview with Andy Williams, who explains what was going through his mind that fateful day when he carried out a mass shooting at his school. Miles also spoke with Liza Long, author of the viral blog post "I Am Adam Lanza's Mother," about Long's son's battle with mental illness and violent behavior. Watch that interview on our homepage.