a silence is broken. a dark mystery explored. >> do you believe in evil? >> how could anyone have missed these signs? >> could you have prevented what happened to columbine? good evening. i'm diane sawyer. tonight, a mother of one of the killers at columbine will speak. what did the parents miss, and are they parents like us?

sue klebold has written a book, "a mother's reckoning," and the proceeds will go to the mental health foundation of america. and before sandy hook and virginia tech, it seems to have begun with columbine. >> reporter: it is 1999, a shock wave hits america. two high school boys in trench coats carrying shotguns, a semiautomatic weapon, and homemade bombs walk into their school and begin the slaughter of their classmates, who were sitting on the grass eating their lunch, who were hiding under tables. no defense from the terror. 13 are killed. 24 are wounded. and we are all watching for the first time. children run out of their school, fleeing mayhem. for the first time, we see a

the window of his high school to escape with his life. and for the years to come, we would all be asking the same questions -- who were these killers? and what kind of parents could produce children like these? >> someone wasn't doing their job. >> reporter: for 17 years now, the parents of dylan klebold and eric harris have lived their secrets, unwilling to step forward. until a grey-haired woman makes her way into a room. in the course of this day, we see her pacing. perhaps grappling with her decision. after years of being, she says, afraid and ashamed. sue klebold is now 66 years old. for the families of the 13 people who died and 24 people who were injured, most of them children. >> yes.

>> reporter: what is it you want to say to them? >> the one thing, of course, that i want to say is, i am so sorry for what my son did. yet i know that just saying i'm sorry is such an inadequate response to all this suffering. there is never a day that goes by where i don't think of the people that dylan harmed. >> reporter: you use the word harmed. >> harmed. i think it's easier for me to say harmed than killed. and, and it's still hard for me after all this time. >> reporter: is that about a certain need to deny what happened? or -- >> i don't know. perhaps. perhaps. it is very hard to live with the fact that someone you loved and raised has brutally killed people in such a horrific way.

the last moments of his life were spent in violence, sadism. you know, he was cruel and hateful and -- and i have to own that. i just remember sitting there and reading about them. all these kids and the teacher. and i keep thinking, constantly thought how i would feel if it were the other way around and one of their children had shot mine. i would feel exactly the way they did. i know i would. i know i would. >> you blame the parents? >> you bet. >> reporter: for all the parents who have said, "well, i would've known something." >> i know. >> reporter: i would've just known. >> before columbine happened, i would've been one of those parents.

i think we like to believe that our love and our understanding is protective. and that if anything were wrong with my kids, i would know. but i didn't know. and i wasn't able to stop his hurting other people. i wasn't able to stop his hurting himself. and it's very hard to live with that. >> reporter: you called him the sunshine boy? >> yeah, we did when he was little. yeah. he had this sort of a mane of golden hair. and it was just always thick and round. and he was such a happy, precocious, brilliant little child. >> reporter: she seems to be trapped in a

she has written a book called a mother's reckoning. in it she says all the lessons of her regret which began on the day she "woke up an ordinary wife and mother fast forward 24 hours and i was the mother of a hate-crazed gunman." on april 20, 1999, she says was at the office where she works helping disabled college students. right after noon, 12:05, her husband tom, a geophysicist, who works from home, calls and says it's an emergency. >> his voice sounded horrible. jagged and breathless. something terrible is going on at the school. >> reporter: he tells her two killers wearing trench coats are shooting kids at columbine high school. one of dylan's friends has called, worried that dylan might be involved. he wasn't there for morning class and he wears a trench coat. tom races through the house hoping against hope to find that coat. >> you always think somebody's making a mistake. >> reporter: it's not there. >> my first thought was, dylan may be in danger. who are these people that are hurting people? >> reporter: she has to drive 26 miles to get home. thoughts racing. >> hyperventilating and trying to talk myself down.

it is official, her son dylan is believed to be one of the shooters, and the shooting may not be over yet. in that moment, she says a searing prayer no parent thinks they could ever pray. >> the police were there and the helicopters were going over. and i remember thinking, "if this is true, if dylan is really hurting people, he has to -- somehow, he has to be stopped." and that -- at that moment, i prayed that he would die. that, "god, stop this, just make it stop. don't let him hurt anybody." >> reporter: and so her quest begins. she says, she goes back over every year of her life with a magnifying glass. looking for the past of her son's descent, and the clues to all the things she missed. that's coming up next. from the lindt master chocolatiers. a hard outer shell with a smooth center.

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>> reporter: look at a kind of class picture. can you pick out which ones will grow up to be school shooters? almost two-thirds will be from two-parent homes. nearly half of the kids will do well in school. 73% of them will never have been arrested before. and yet, every child you see here will become a school shooter. in total, murdering 67 people. the child in this picture is dylan klebold. in her book, his mother writes he wasn't the pinwheel-eyed portrait of evil we know from cartoons. he was shy, likeable, with hands-on parents. >> -- who put them to bed with stories and prayers and hugs. >> reporter: the klebolds, the family who lived in this house in the foothills of the rockies. their two sons named after famous poets. sue klebold calls dylan her shiny penny. in gifted classes, loved little league, gave big hugs and kisses and built tall ships out of legos.

>> and he wouldn't just work on one puzzle, he'd dump them all into a big mountain so that he could solve five or six of them at the same time. >> reporter: sue klebold says he was easily embarrassed. tearful and hard on himself if he made a mistake. he's shy heading into adolescence. >> he talked about looking weird. he was a tall, gawky kid with glasses. >> reporter: but he has friends, goes out to parties. friday night bowling with friends. she says some of his friends decide it's cool to look different from the jocks. they buy long black coats. but didn't you wonder why he wanted a trench coat? what was that about? >> well, i -- i -- >> reporter: a trench coat? >> -- was the kind of kid who loved to look different. i mean, i -- i was an art major. >> reporter: she says she does notice something, that dylan seems to be losing interest in good grades. he builds his own computer and spends more time alone in his room. and sometimes he is moody and irritable. but she now says, as she looks back over her life, she is making a big mistake.

writes off the changes as an adolescent phase. >> sometimes he would seem -- you know, distant or quiet. and i remember asking him, "are you okay? are you sure you're okay? you seem so tired." and he'd stand up and say, "i've got a lot of homework. i just, i need to go to bed." >> reporter: and you let it go. >> and i let it go. and that's the difference. i would dig. if it were me today, i would dig and dig and dig. i had all those illusions that everything was okay, because, and more than anything else, because my love with him, for him was so strong. i felt that i was a good mom. that he would, he could talk to me about anything. part of the shock of this was that learning that what i believed and how i lived and how i parented was an invention in my own mind. >> reporter: she says she hopes other parents watching tonight will think about what a child can be hiding. it's the summer after dylan's sophomore year, long before columbine. she has a journal and in it

she's writing, "things have been really happy this summer. dylan is yukking it up. having a great time with friends." she has no idea her 15-year-old son has begun a secret journal of his own and his first entry is this. "thinking of suicide." "i hate my life, i want to die. i have a nice family, good house, couple of good friends. no girls. nobody accepting me, even though i want to be accepted." he plays the nine inch nails song "hurt", and makes a list of all the people he loves who will never love him back. >> hi, i'm dylan. >> reporter: you can see him in this video. his junior year at columbine. he seems self-conscious. a little wistful. but talks about the future, the classes he'll take to help get into college. >> so i get better chances after high school as far as colleges go. maybe a scholarship? >> okay, let me ask you this, are you an independent learner or a group learner? >> probably independent. >> repor

80% to 90% of depression can be treated and even suicidal depression is not an explanation or pathway to violence. but dr. gregory fritz, president of the american academy of child and adolescent psychiatry, wants to warn parents tonight that suicidal depression is real and can strike any teen anywhere. >> somewhere between 15 and 20 percent of high school kids say that they have thought about suicide in the past year. >> reporter: let me repeat. 15% to 20% of adolescents seriously consider suicide. and that's at least one child in every american classroom. every 95 minutes, a young person will take their life. fritz says a lot of loving parents can miss something serious, sure that changes are just a phase. >> i've felt that as a parent myself. just, "oh, please, don't let it be so, i don't want to see it, i -- won't this go away, it's just a phase."

the good news is, oftentimes it is. it can lead us to have blind spots. >> reporter: on the internet, thousands of kids make secret confessions. a teenage girl who seems to smile. >> just like this eternal sadness. >> reporter: a high school star who says teenagers are better than adults at hidin depression. they're so afraid of the stigma. >> if you were to look at my life on the surface, you'd see a kid who was the captain of his basketball team. consistently on the honor roll and consistently at every party. so you would say i wasn't wasn't suicidal, but you would be wrong. >> reporter: later in this broadcast, we'll tell you more about spotting teenage depression, dr. fritz taking questions online. but more than 17 years ago, sue klebold said she knew so little about teen depression, thinking the big problem in her house was her older son grappling with drugs. were you distracted? >> well, of course, because we're human. i mean, we all have things that distract us. you can't say, "i was too busy to notice that my son was falling apart." >> reporter: and heading down a

path of destruction. could you have prevented what happened at columbine? >> if i had recognized that dylan was experiencing some real mental distress, he would not have been there. he would've gotten help. i don't ever, for a moment, mean to imply that i'm not conscious of the fact that he was a killer, because i am. >> reporter: a year and a half before the columbine massacre, her son is a junior, a series of troubling events. he hacks into the school computer system with some friends. they are all suspended for three days. next, he scratches an epithet on a locker of a kid he thinks is taunting him. and then the big shock -- on the same day he makes that video talking about his future, he and another kid break into a van, steal electronic equipment and police make an arrest. this is a felony. two felony counts -- >> it was terrible, i know. absolutely. it was awful. and at the time, i thought that was the worst thing i could ever possibly experience. >> reporter: dylan's cold reaction after the arrest scared and shocked her.

he acted as if he had done nothing wrong. she says she gave him one of her lectures, trying to reason with him. >> i even talked about the ten commandments. i said, "it's wrong to steal. under -- in no circumstances, is this -- this right." and then we responded as most parents would. we took away privileges. >> reporter: she says a lot of days he was affectionate, planning for the future, applying to colleges. she didn't know he was writing in his journal how he "wanted to get a gun to use on a poor s.o.b." himself. one night, she's frustrated he's not doing chores. she pushes him against the refrigerator. >> i pushed his shoulder and i held my hand against him. and i said, you know, "you've got to stop thinking of yourself." i gave him the old mom lecture. and -- and then i said, "and, by the way, today's mothes day and you forgot it."

and i don't remember how that confrontation ended. i just remember he softly said, "mom, please don't push me. i'm -- i don't know how much i can control myself." it wasn't a scary thing. it was just him being nice to say, "back off, please." >> reporter: she says she blamed herself for pushing him too far. >> and then he went out and he got me a gift. a little -- it was a little water can with african violets in it. and i thought everything was fine, because he was so -- he was so sweet. >> reporter: and inside, on his way to becoming a mass shooter. and there is no way to continue telling this story without going back to another little face in that class picture, a friend who was with him breaking into the van -- eric harris.

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is there anything that may have stopped the massacre at columbine? we study pieces of a puzzle. >> i couldn't believe that someone like dylan could intentionally hurt other people. it was inconceivable that that could be something he could do. >> reporter: we brought in former fbi agent mary ellen o'toole, one of the world's leading profilers of the criminal brain.

pages of evidence on columbine and dylan klebold and she concluded there is a turn he's about to take. >> i don't think he was always a violent, young man. i think it evolved over time. >> reporter: you don't think school shooters just snap one day? >> absolutely not. i have not ever seen where that -- where that has happened. i think he was in a very destructive friendship, which was very powerful. maybe even more powerful than what we think. >> reporter: which takes us to another house, another set of hands-on parents. a friend said retired air force pilot wayne harris was like a leave it to beaver dad. >> of course i met his parents. we wouldn't have allowed our children to play with anybody that we hadn't met their parents or been in their home. >> reporter: their son eric has been a pal of dylan's since the seventh grade. no one knows he too has begun to keep a secret journal. and his journal is filled with venomous threats, graphic fantasies about revenge on people who've insulted him, people engulfed in flames, decapite

according to o'toole, eric's sadistic cruel ramblings signal a personality disorder. a psychopathic brain. he calls his writings "the book of god." >> these are people without a conscience. these are people without empathy. without guilt. >> reporter: but is eric harris really different from dylan klebold? another expert on columbine, dr. peter langman, insists he is. >> eric liked to draw weapons. he drew swastikas. he wrote about the nazis. now, dylan drew hearts. dylan wrote about his search for true love. eric, when he does refer to girls, is his fantasies of raping them. >> someone who really is psychopathic is incredibly charming, they're manipulative. they are engaging. >> reporter: eric writes about his ease, going back and forth in a double life. here he's in court after the arrest on the van incident talking to the magistrate with great respect. >> what kind of grades do you get?

>> "a"s and "b"s, your honor. >> what's your curfew? >> 10:00 on weekends and 6:00 on weekdays. >> reporter: the court sentences the boys with leniency. a year of counseling and community service. sue klebold has been told by another mother that eric harris is prone to angry, terrifying outbursts, but klebold thinks it's an overreaction because around her eric is so polite. and so, like many other boys, they play video games like "doom." they both like violent movies and making little movies of their own. trying on what it's like to be tough guys. in this one, pretending to be heroic government agents, out to save the world. eric is smooth. >> i think we might have to get more weaponry. >> reporter: dylan stumbles. the camera shuts down. and there is something else about the two of them that keeps coming up in research about

other school shooters, too. 85% of these shooters are adolescent boys. so many feeling rejected by girls. the experts point to a crisis in masculinity during puberty. and there's a solution they get from everything they're seeing. >> in so many films and so many videogames you can pick up a gun and instantly you have power. >> reporter: eric writes, "everyone is always making fun of me because of how i look, how weak i am. guns -- i need guns." dylan asks for one too. >> he asked me if i would buy him a gun. and i had told him no. >> reporter: what was your policy on guns in the house? >> we kept no firearms in the house. sue klebold says she used to look through his room during his junior year, but by his senior year she dec

desire for privacy. with distance and regret she now says how wrong that decision was. would you ransack his room now? >> i would. i'd do it as if his very life was depending on it. and i would do it with love. now, in doing something like that, we are violating privacy. >> who's ruling the roost? if that room that you pay the mortgage on is being cut off from you so you can't go in there, you have a problem. now, does that mean they're going to go out and commit a mass murder? not necessarily. but you have to know, you have to understand what's going on with them. >> reporter: the boys were already getting their hands on guns and hiding them. a girl, a school friend old enough to buy them legally bought them three at a gun show. and they get another gun, a semi-automatic, from a private seller. they train at a range. eric harris now writes, we have guns. i feel more godlike. and dylan klebold writes he now has a choice. committing suicide or go nbk with eric. nbk, "natural born killers," the violent revenge movie by oliver stone.

which brings us to the central question about dylan klebold. why did he go from suicidal to homicidal? did eric infect him with a kind of pathological virus or was it dylan's presence that reinforced eric's violent fantasies? do you think dylan klebold knew right from wrong? >> yes. absolutely he did. but it did not preclude him from being able to participate in the planning, to go through with it, to enjoy the planning, and to carry it out. >> reporter: i think everyone can accept he was depressed. do you think he also had another mental disorder? >> possibly. i think that's possible. i can't tell you what it might've been.

evil? >> i don't think so. i don't think i do. >> evil is a spiritual term. and it doesn't have any legal or behavioral meaning, and so i stay away from it. >> reporter: at this point, the clock is ticking down. it is now two and a half months before the massacre. a mother worries about her withdrawn son but allows herself to be reassured when he is released early from community service with a glowing assessment of his bright future. >> he's a good kid. you don't need to worry about dylan. >> reporter: then one month before the massacre, a final warning signal. a man in a story that looks like him pulls out a gun and commits acts

the teachers call the parents in. >> she said it contained some bad language. and she said, well, i'll tell you what. i'll show it to the school counselor and see what he thinks. and i said, so you'll call us if you think there's a problem. >> reporter: the question asked is, why didn't you demand to see a paper that had worried the teacher enough to send it to a counselor. we reached out to that school counselor, now retired, who read the story. he told us, in a pre-columbine world, he just didn't see it as a threat. that's not a red flag? >> it's not a red flag that would be indicative of someone absolutely going out and becoming violent. but it's enough of a red flag to say, okay, let's get going. let's take a look at this young person. >> reporter: and o'toole says if everyone had taken a look, it's striking what could have been seen. it turns out the boss at the pizzeria where dylan worked had seen the two boys experimenting with a pipe bomb.

specialist, a psychologist who apparently missed the plan. and perhaps most shocking of all eric has a website. 10 pages of threats. police started to draw up a search warrant and then did nothing. 17 years ago, they were all holding pieces of a puzzle, and no one put them together. >> if you're wondering why you haven't heard from sue klebold's husband tom, she says they're divorced, driven in different directions by grief. and he's chosen not to speak publicly. when we come

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>> reporter: the weekend before the massacre at columbine, dylan klebold gives a kind of gift to his mom who has urged him to go to the prom.

in fact, the girl who bought three of the guns. he dances through the night, dressed up in his tuxedo. all the time knowing four days later he is going to dress up again, arm himself and go to school to kill and to die. the ou autopsy says, by suicide. april 20th. >> we all got up very early. i hear him bounding down the stairs, past our bedroom door, and really going quickly and heavily out the door, as if he were late and i yell, "dyl," and he yelled, "bye," and then sort of slammed the door. >> reporter: you said it was edgy, nasty -- >> it was. >> yeah, it was, "bye." >> reporter: her husband tom says he's going to talk to dylan when dylan comes home. >> columbine high school. >> a community in shock. >> media attention from around

the country. >> bloodbath. >> dylan klebold. >> reporter: the klebolds flee their house, living, she says, like desperate nomads. despairing. the surreal agony of cremating her son. in her journal she writes, some days i was worried about losing my sanity. after several weeks, she goes back to the state community college system. >> i'd turn on a radio and people would be talking about me and calling me a disgusting person. >> reporter: she says a saving grace, the friends who still believed in them. when they were in hiding, their neighbors posted a sign on the driveway. sue and tom, we love you. we're here for you. call us. and her colleagues at work help camouflage her presence, no sign on the door. but you could have escaped with a different name. >> i did think about it. but the real thing that it-- i finally realized was that i can't run from this. changing my name and moving doesn't allow me to leave this behind.

>> reporter: she says for months and months, her mind was looking for any way to deny the truth. maybe dylan was on drugs. maybe he was forced to be there. she reached out to the victims' families, writing letters, but calling the incident a moment of madness. >> i believed this was a moment of madness. i believed this was some impulsive fluke that happened suddenly. >> reporter: then six months after columbine, her denial is shattered. the klebolds get a call from the lead investigator in the case who brings them face to face with the inescapable truth of the evidence. dylan took part in months of planning. in the purchase of the guns. and building 99 explosive devices, most of which failed to detonate but were intended to kill hundreds and hundreds of people. and there he was on videotape recorded as a kind of countdown to the attack.

twisted manifesto of hate. >> it was horrible to see those tapes. they were posturing. they were acting tough. they were talking about all the horrible things they were planning to do. i remember at one point standing up, because i thought i was going to be ill. and like i might have to run out of the room. >> reporter: she will make herself confront every merciless shot her son fired. she decided to put it in her book. >> i try to be as honest about that as i could. i didn't want to make it graphic. but i wanted to make it honest. because, you know, from a mother's perspective, of course, there is a tendency to want to soften all the horrible things that he did. >> reporter: but as we said, she lives in the hell of that contradiction. she has said, i saw the end product of my life's work. i had created a monster. but still inside her, a mother's love for a son she lost. she hears the final word on the tape.

he says, hey, mom. i got to go. "just want to apologize for any crap this may bring. just know i'm going to a better place. good-bye." >> he said, "mom." just the fact that he said it meant a lot to me. yeah. >> reporter: the tapes, never released. we're told they've now been destroyed. she writes in her journal, "all i want to do is die." then, two years later, the woman who prayed to die is diagnosed with breast cancer. she says during the treatment, something made her try to live and turn the horror into purpose. >> you get to the point where you have to just sort of say, "i can't -- i can't stay with this level of intensity." and i just want to let -- i have to let some of it rest and say, "i didn't kill these people.

dylan did. it wasn't me." >> reporter: she says she begins a quest to learn about violence and what she missed. lessons in the book. >> i'm donating the money. i want to make sure that we -- i give the money to mental health organizations and suicide prevention. and i don't know what else i can do. but i felt that i had to do everything i could do. >> reporter: she talks to the parents of suicidally depressed kids about the way she wished she had probed and not dismissed, or tried to fix everything. >> you listen and you don't judge. and you don't react in terms of, "oh, my god, you can't think that. you can't possibly feel that way." >> reporter: dr. fritz says start by making time to sit in silences, open-ended questions. you don't need to have answers. >> how did that happen? you must have felt terrible when

that happened. i would have felt terrible. >> reporter: would you ask, "do you feel suicidal?" >> absolutely. if a parent is worried about that, they should say that to -- they ask the kid. >> reporter: can you plant that idea in the mind of -- >> i've interviewed hundreds and hundreds of kids who've attempted suicide and they never said, "oh, somebody asked me about it and that tipped me over." they're thinking about it long before anybody asks and oftentimes it's a relief to have somebody ask. >> reporter: and sue klebold also talks to those other pariahs, the families of other school shooters. so we had a question, what about the parents of eric harris? does she blame them for what they missed? >> i don't blame them. i don't. they are not eric. >> reporter: have you talked to the harrises recently? do you want to? >> i do talk with them occasionally. i don't feel able to represent them in any way. and i want to make sure i protect their privacy. >> reporter: that is all she would say. the harrises would not return our calls.

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more shots being fired at the tower. >> reporter: it is august, 1966. >> austin, texas, was held in the grip of a terror whi

in killing and ended in killing. >> reporter: american television is riveted on a college student former marine charles whitman. the son of an abusive father. he climbs to the top of the university of texas tower, shoots and kills 14 people, wounding 32 others before he is taken down. it is hard to believe, after whitman, it would be another 30 years before a school shooting with such a high death toll. especially since after columbine, there's a steady stream of assaults. law enforcement says 50 rampage school shootings and abc news has estimated at least 79 thwarted plots, more than half of them mentioning columbine. >> columbine was a new kind of shooting. like a military mission. we're just seeing one right after another and each one learns from the other, which also is very concerning. it's not just copycatting. >> reporter: we reviewed cases over the years and found that the number of younger shooters

since columbine. o'toole says she's worried about a generation raised on violence, videogames, movies. and take a look at this study. it shows today, even a pg-13 film has triple the gun violence it used to have 30 years ago. >> when you look at the shooters now, many of them were born into this culture of violence. that's what they grew up on. whether it's movies or books or social media. their brains became hardwired on violence. >> reporter: is this documented, though, that -- >> no. but i think many of my colleagues have the same fear that this thing has morphed and changed since columbine. >> reporter: what role do you think access to guns played and plays in these? >> you cannot carry out a mass murder without weapons of mass destruction. you can't do it. >> reporter: and in america 68% of school shooters get their guns from relatives or at home. >> for example, japanese young men love violent video games. they buy more of them than we

but you don't see mass murders over there. >> reporter: she says it is a different culture. but also, in japan, it's difficult to get guns. compare, six gun deaths in japan in all of 2014. 33,000 here in the u.s. so what can we do about the shooting at schools? mary ellen o'toole wrote the nation's manual on how to prevent them. through what's called threat assessment. and as we said, since 79 have been thwarted, prevention can work, but how? in dozens of cases it is fellow students who have overheard something, tipped off authorities, who act as a team to assess the seriousness. >> we could be having a very different news conference today had this plan gone through. >> reporter: in other cases, they are complete strangers who act on intuition. a clerk developing pictures at a drugstore. >> there was pipe bombs with nails taped to them. >> reporter: police went to a home and found a vast arsenal of weapons and explosives and a mention of columbine. as we said, most mass shooters are boys.

girls. like katie. >> it's absolutely terrifying to be the person who has to come forward and say this because you don't know. >> reporter: terrified, but making her choice. >> what if i didn't say something? i'd have to live the rest of my life knowing that. i'd almost feel just like i was just as much to blame as they were if i didn't say something. >> all right, guys, see you later. >> reporter: police officers like captain cheryl newman-tarwater in los angeles are asking for everyone's help in the race against time. her unit alone has 37 ongoing cases. >> it's not about everyone tattling on each other, i'm going to tell on you. it's not about that. it's about looking at your environment and wanting it to be as safe as possible and wanting to help folks get help if they need it. >> reporter: need it like this young man, who has come forward in shadow to make an appeal. he was once a depressed teenager talking about a plot of violence against other students. but some of his classmates

is. for his wife, family, career, and his second chance. >> for the love of god, reach out and talk to someone. it could be your parents, it could be the school guidance counselor. if i can say something tonight, no matter how small it is, to maybe help even one person, who went through something similar to what i was going through, then i guess it'd all be worth it. >> anyone can be the person who observes the behavior and decides that they will not interpret it themselves. most of the time, frankly, it is a nothing. but maybe it's just that one peek into what could be the next columbine.

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we are very near my old house. >> reporter: sue klebold says today, joy is really just a moment without suffering. >> isn't this beautiful? >> reporter: she knows no suffering like that of the victims' families. last week, we tried to call every single family. some of them expressed anger, like the father of daniel rohrbough, who said except for the letter she wrote, he never heard her say she's sorry. we don't know if he watched tonight, but this is what he said years ago. >> there's a false teaching that says forgive everyone, god forgives everyone. but he doesn't, he never forgives the unrepentant. >> reporter: patrick ireland, the boy wh

brain injury, said he just wants to forget their names and move on. but other families told us they want to offer sue klebold their prayers and their grace. rachel scott was the first to die at columbine. her family has a foundation teaching forgiveness, because they say it's the way god flows through us to help others. anne marie hochhalter, a bullet paralyzed her from the waist down. >> i realize that holding onto that anger does nothing. you know, it just brings you down. >> reporter: tom mauser, who wears his son's shoes as he makes his way through life on a mission. for daniel, he fights to keep guns out of the hands of kids and criminals. he told us he actually met with sue klebold, and the meeting helped turn his anger into understanding. and she says tonight, she wants the families to know she's ready to offer anything else that will help. >> i don't want to impose myself to do that, because it has to be about them and what -- and their healing and what they need. >> reporter:o

someone said, sentenced to a life of grief, with no parole. after our interview is over, she walks outside in the foothills of the rocky mountains and tells us sometimes she finds herself drawn to a place that has a plaque with these words -- "it brought a nation to its knees. what have we learned?" it's the columbine memorial. >> i feel, kind of, unwelcome there. like, you know, of course. that perhaps i'm intruding. >> reporter: but someday, if you go to that memorial, you just might see a grey-haired woman sitting there -- quietly, alone. >> i've spent quite a bit of time there. but i don't go there often. sometimes, i just sit there and think.

and i tell them i'm sorry. yeah. >> we will have so much more about all the issues raised tonight on abcnews.com, and social media. and we will be reaching out again to the families of the victims, to hear more from them. we hope this has created a conversation tonight. let us know about lessons we can learn, and how to prevent it from happening again. i'm diane sawyer. >> first at 11, storm watch. a winter weather advisory, now

you saw a small squall. but good news is they're winding down. this hour,story at the cold! we are talking about temperatures dropping 20 degrees. weekend thisst winter. >> that's all. just 20 degrees. that's all. ha ha! latest on the temperatures. >> and the wind chill factors, 15 degrees below zero. >> oh! >> that's the big change on the way. taking a look at the light snow there right now, it's not going to amount to a whole lot more. towards is moving off the east. that winter weather advisory for just about another hour or so, did see the you who snow, it was anywhere between a inch.g to maybe a half all this moves away from us. looking at light, light snow at hour. a lot of it, not even reaching the ground. this is what's on the way, later on tonight. big, big push of very, very cold air. it will arrive tomorrow morning tomorrow morning, through the day, and into the day on sunday, we're