60 Minutes reports: Tragedy in Newtown

The following is a script of "Newtown" which aired on Dec. 16, 2012. Scott Pelley is the correspondent. Nicole Young, Bob Anderson and Michael Radutzky, producers.

It is a Sunday of sorrow for Newtown, Conn., and for the nation. This afternoon, hundreds of residents walked the road to Sandy Hook Elementary School where, on Friday, 26 people were murdered, 20 of them children in the first grade. President Obama has been in Newtown tonight for a memorial service.

First reports of this tragedy have turned out to be inaccurate. We were told that the gunman's mother was a teacher at the school, that he was allowed in because he was recognized, and that he targeted his mother's classroom with two handguns. Well tonight, we know that all of that is wrong. Here's what we do know as told by people who knew the gunman and by one woman at the school that he approached, but did not kill.

That woman is Sally Cox, the school nurse. This picture was taken shortly after she left Sandy Hook Elementary on Friday. She's been the school nurse there 15 years. And she told us that Friday morning began with comforting routine; 9:10 Pledge of Allegiance, 9:15 outside doors locked. Then came 9:30.

Sally Cox: All of a sudden I heard a very loud popping noise. I mean a noise that I've never, ever heard before. And my first thought was, was this something with the heating-- something-- or did something fall? And, I called out to the secretary, "Barb, what is that?" And then she called out to me by name. She said, "Sally." And I could just hear, like, fear in her voice.

Scott Pelley: It was something about the way Barb called out your name?

Sally Cox: Yes. Yeah. She just had this horrible sound of fear in her voice. That's what made me just-- 'cause I think I was about ready to go to see what was going on. The popping kept going off. And I just dove underneath my computer desk. The back of the desk has a small opening for, like, wires to come out. And I just peeked. I could see his feet and his legs from the knees down. And he-- his feet were facing in my direction. And I just froze with fear. And then he just-- it was just seconds and then he turned around and I could hear him walk out. I heard the door close and then I just heard popping starting all over again. And then the secretary, she was down behind my desk and we pulled the phone off the desk and she called 911.

Scott Pelley: And she said what?

Sally Cox: She said-- I-- she said, "We have a shoo-- please send help right away. We have a shooter in the building." And then we just wanted to get out of there. And then we just ran into my big supply closet and we ran into the closet. We pulled that door closed. So we were behind two locked doors. And we could just hear the popping continue. And we heard screams. There's nothing we could do. You know? It was just a helpless, horrible feeling. You know? And just like a nightmare that-- couldn't believe that-- you know, you just think it's a bad dream. After some time, I think it was about 11:15, so we had been in that closet for about an hour and a half, I opened the door and I peeked out, 'cause my office has a lot of windows and looks into the courtyard. And I just saw what looked like maybe SWAT people but I didn't know, you know, who they were. I didn't know if there were other shooters. And it wasn't until 1:15 when I-- somebody was jiggling the door. And-- but nobody called out. So I decided to be brave enough and open that door into the office and a lot of state police officers were there at that point. And they were very surprised to see me.

Scott Pelley; You were in the closet for about four hours?

Sally Cox: Close to it. Yeah. Yeah. Just fearful.

Scott Pelley: I wonder what the standard security at the school is in terms of allowing visitors into the building and that sort of thing. How is it supposed to work?

Sally Cox: We do our Pledge of Allegiance at 9:10. And then five minutes later the doors are locked. All the doors and all-- going around the whole building. And then when be--when people come they have to buzz. There's a camera. They push a button. It buzzes in the office and we buzz them in.

Scott Pelley: How long has that been true?

Sally Cox: Four or five years.

The gunman had shot out a window to get past the locked door. From the start, Sally Cox told us, the teachers and the kids, went immediately into the lockdown that they had practiced and practiced.

Scott Pelley: Children were trained to go under their desks in events like these?

Sally Cox: Yeah, yeah, yeah. And we have different kinds of drills, you know? I mean-- in addition to fire drills and high wind drills and lock down drills and evacuation drills. So we've-- we've done it. We've been doing it, you know, each month it's something different, you know?

Scott Pelley: So you'd done those kind of things fairly recently?

Sally Cox: Just recently, yep. Yes. Yeah.

Scott Pelley: At some point, you left the school. And I wonder in that journey from your office through the door, what did you see?

Sally Cox: They told me to close my eyes. They-- they got-- they took my arm. And they guided me out. They said, "We'll guide you out. We want you to close your eyes until we get to the parking lot." I don't know what was there that they didn't want me to see, but they told me to close my eyes.

Scott Pelley: And that's what you did.

Sally Cox: That's what I did. Yeah.

The officers spared her the sight of the bodies of 20 first graders, four teachers, the school psychologist, the principal, and the killer.

Twenty-year-old Adam Lanza lived in town nearly all his life but he left few impressions. Olivia Devivo sat behind Lanza in 10th grade honors English.

Olivia Devivo: Yeah. He carried a briefcase, briefcase to every class. And that stood out to me because in high school everyone has backpacks and you know messenger bags. And that stood out to a lot of kids.

It also stood out that Lanza was uncomfortable when asked to speak in class.

Olivia Devivo: He just would just get very nervous. And you know, his face would turn bright red and he would get very fidgety. And you could just tell that it wasn't that he didn't know the answer. It's just that it was very difficult for him to say what he wanted to say.

Scott Pelley: Did he have a reputation for being a smart kid?

Olivia Devivo: Yeah, definitely. I mean you can just tell by the way he was in class. He was always-- appeared to be very attentive and focused.

Scott Pelley: How would you describe him socially?

Olivia Devivo: He must have really felt uncomfortable in any kind of social situation because he never really put himself out there. And I just don't really remember him ever, you know, stepping forward or really saying anything. It was just he wanted to be left alone and we left him alone.

She doesn't remember Lanza after that, maybe because he wasn't going to the high school full-time. Family friends told us that he was being home schooled by his mother Nancy Lanza. Nancy Lanza told her friends Mark and Louise Tambascio that Adam was brilliant but disabled.

Scott Pelley: Did Nancy Lanza ever tell you specifically what her son's medical condition was? And she put a name to it?

Mark Tambascio: Asperger's.

Scott Pelley: That's what she said?

Mark and Louise Tambascio: Yeah. Yes.

Scott Pelley: That it was Asperger's syndrome?

Mark Tambascio: Absolutely. There's no question.

Scott Pelley: And for her it was a full time job taking care of him?

Mark Tambascio: Absolutely. Oh my goodness, yes.

Asperger syndrome is a disorder within the spectrum of autism. It's characterized by social impairment, communication difficulty and repetitive patterns of behavior. An Asperger's support group told us today that patients are more prone to be victims of violence than the perpetrators of violence. And we don't know whether Asperger's played any role in the shootings, but friends told us that the condition did dominate the Lanza's lives.

Louise Tambascio: I mean, I know he was on medication and everything, but she homeschooled him at home cause he couldn't deal with the school classes sometimes. So she just homeschooled Adam at home. And that that was her life.

Scott Pelley: She wasn't working. She devoted her time to Adam?

Louise Tambascio: Yeah, she didn't have to work, so that's what she did. She homeschooled him and you know and she did a lot of charitable work and everything.

Nancy Lanza appeared well off, living with her son in an upscale home. She was 52, divorced in 2009, with another, older son. In town, they say she was friendly and generous, donating time and money to charities. Nancy Lanza also made a hobby of shooting sports. She owned several guns. A friend said that she'd grown up that way on a farm in New Hampshire.

Mark Tambascio: Yeah, she was. She liked to target shoot. You know, she got into it I think in you know, the last few years or so. She really enjoyed it. But yes she was an advocate she really got into it and loved it.

The guns Adam Lanza carried into the school, a rifle, and two pistols like these, were all legal, registered to his mother, under Connecticut laws which are among the strictest in the nation. The murder weapon was a semi-automatic variation on the M-16 assault rifle. It fires one round with each pull of the trigger. The first victim Friday was Nancy Lanza. Police say they found her lying in bed, shot in the face. They also discovered the computers in the home had been smashed to bits. An FBI lab is trying to recover documents from the hard drives now. And investigators will subpoena the Lanza's emails and text messages from service providers.

Motive is still a mystery. But if anyone can begin to understand an attack like this, its Robert Fein and Bryan Vossekuil. In 1999 they went into prisons to interview and study assassins and would-be assassins for the U.S. Secret Service.

Then in 2002, the Secret Service published their follow-up study on 37 school shooters.

Scott Pelley: Robert, you've been speaking to people who are involved in the investigation at the highest levels. And I wonder what they're telling you about these early days.

Robert Fein: Fundamentally, what I hear is that this is a very complicated case. A very difficult, painful case that's going to take a long time to really unravel and understand.

Scott Pelley: What are they saying about precedents and how this compares?

Robert Fein: On the continuum of lone-offender attacks, this case is described as way out there on the continuum in terms of awfulness.

They discovered that most attackers followed a discernible pattern of behavior for weeks or even months before the attack. They call it "the pathway to violence."

Scott Pelley: How does this pathway to violence manifest itself? What is it that people can look for in-- in a person who is on this pathway, as you describe it?

Robert Fein: People who engaged in these attacks took a series of actions as in often selecting a particular weapon, sometimes practicing with a weapon. They thought, "I'm desperate." They accepted the idea that violence might be an acceptable way to solve their problems.

Scott Pelley: In how many cases did the shooter tell someone essentially what he was planning on doing before he did it?

Bryan Vossekuil: In almost all of them, the student who committed the attack, the school shooter, communicated, in many instances, the-- his intent to commit the attack.

Scott Pelley: The events of Friday struck fear into the heart of every parent who sends a child to school all across this country. I wonder what you would tell the folks at home who worry, "Can I send my kid to school on Monday?"

Bryan Vossekuil: It is important to remember that these are extremely, extremely rare events.

Robert Fein: Any event as horrible as the attack of last Friday scares everybody. But the reality in this country is that schools have been and are safer and have become much safer over the last several years.

Yesterday in Newtown, they released the names of the lost. We were surprised when school nurse Sally Cox told us that she was making a point of not hearing them -- not all at once anyway. Better to take 26 blows one at a time.