nearly two decades later, sue klebold is speaking out. the mother trapped in contradiction between a little boy and all she believed he could be and the murderer he became. and especially for the families of the victims, those urgent and anguished questions never answered, until now. prevented, and warning signs that may have been missed. here's abc's diane sawyer. >> 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 kill the. 24 are wounded. and we are all watching for the first time children run out of their school fleeing mayhem. >> a lot of students -- >> coverage of the columbine -- >> reporter: we see a wounded student struggling out 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 -

some said they wanted to offer sue klebold their prayers and grace. so many people, as 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. it's the columbine memorial. >> i feel a kind of unwelcome there. like, of course. that perhaps i'm intruding. >> reporter: but someday if you go to that memorial, you just might see a gray-haired woman sitting there quietly alone. >> sometimes i just sit there. and think. and i tell them i'm sorry. >> reporter: for "nightline," i'm diane sawyer. >> our thanks to diane sawyer. sue klebold has written a memoir called "a mother's reckoning: living in the aftermath of tragedy." all the book's profitsless toward research and charitable we'll be right back. shopping for an suv? well, this is the time. and your ford dealer is the place, to get 0% financing for 60 months on a ford suv. that's right. just

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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. 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 th

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 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 w

in her book sue klebold writes, cartoons. he was shy, like bible, hands-on parents, put them to bed with and hugs. >> reporter: sue klebold calls dylan her shiny penny. in gifted classes. loved little league. gave big hugs and kisses.ut of legos. >> he wouldn't just work on one puzzle, he'd dump them into a big mountain so he could solve five or six of them at the same r: she says he was easily embarrassed, tearful and hard on himself if he made a mistake. >> he talked about looking s a tall, gawky kid with glasses. >> reporter: she says she does notice something, that dylan seems to be losing interest in good grades. but she now says, as she looks back over she is male a big mistake. her son is changing. but she writes off the changes. as an adolescent phase. >> sometimes he would 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 need to go toou'd let it go. >> i let it go. and that's the difference. i would dig. if it were

sue klebold told diane sawyer at one point she realized she could not run away from this. >> she talks about the shame, she talks about fear. >>reporter: answers to questions that haae lingered klebold accepted any responsibility for what 1999? >> i think she has gone back over her life she says and try >>reporter: the events of april 20, 1999 forever change the lives of students, teachers and administrators at columbine. images and facts permanently embossed in colorado's history, in america's memories. >> these are kids at high school what in the world is going on here. >>reporter: one of the first reporters to arrive at % columbine the initial call a drive-by shooting. in the investigations that followeddwe learned eric harris and dylan klebold have planted bombs were attempting to blow up the school ann kill several -`hundred. >> they hated everybody. they said they all deserve to die and we deserve to die too. >>reporter: one of a half-dozen reporters after the shooting watched him klebold. >> what is very clear from these tapes is that these two make this was a meticulously plann

she wanted to see what sue klebold had to say. lindsay watts has more. >> reporter: casey johnson says 17 years later she still thinks about what happened that day at columbine nearly every day. reminder. out thh front. >> reporter: and she says the two shooters showed no mercy. they yelled at her after attacking her, johnson says she closed her eyes and played dead to try to survive. she tells us she has no angry feelings toward sue klebold or any of the parents of the shooters. about what they saw from the boys. she is now focused on her own four children protecting them and being ggateful for them. >> every time i drive up to the schoolland drop them off, i'm saying a prayer for the school and for my kids and every single day i pick them up, i'm thankful to be bringing them home. it's a real choice and battle for me to let them out the door >> reporter: we also heard from another columbine survivor who was left paralyzed by the attack. she has writttn a letter to sue us. it reads in part i have no ill will toward you just as i

nearly two decades later, sue klebold is speaking out. the mother trapped in contradiction between a little boy and all she believed he could be a the murderer he became. and especially for the families of the victims, those urgent and anguished questions never answered, until now. constitute massacre have been prevented, and warning signs that may have been missed. here's abc's diane sawyer. >> reporter: it is s 1999. a shock wave hits america. two high school boys in trench coats carrying shotguns, a semiautomatic weaponand homemade bombs walk into their of their classmates. who were sitting on the grass eating their lunch. who wer hiding under tables. no defense from the terror. 13 are kill the. 24 are wounded. and we are all watching for the first time children run out of their school fleeing mayhem. >> a lot of stunts -- >> coverage of the columbine -- >> reporter: we see a wounded ststudent struggling out the window of his high school to escape wh his life. and for the years to come, we would all be asking the same questions -- who

sue klebold has written aok, "a mother's reckoning," and the proceeds will go to the foundation of america. and before sandy hook and virginia tech, it seems to have begun with columbine. 1999, a shock wave hits america. two high school boys in trench coats carrying shotguns, a 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.nded. and we are all watching for the first time. school, fleeing mayhem. see a wounded student struggling out the window of his high school to 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? 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.-haired woman makes her way into a room. in the course of this day, we see her rhaps grapple ing with her decision. being, she says, afraid and ashamed. 13 people who die

they do -- some do question sue klebold's timing in doing this. >> i just remember reaching -- reading about all of these kids. [ crying ] the teacher [ crying ] >> reporter: it is a powerful -- topic. >> i constantly thought of how it would feel if it were the other way around.>> reporter: some have sent messages of forgiveness such as this one from anne marie hochhalter. others are respooding in a far different way. >> every time this comes up again, it opens up that won't. >> reporter: we have talked with many victims parents over the last several days, asking them how they want to respond to seek we bolts -- sue klebold's decision to talk. there is concern over her motivation and questions about why now. >> i think the concern is, for those families, they never got a satisfactory answer from them. they never felt that the -- klebolds never spoke to them in the past.>> reporter: one of the key questions parents wwnted answered -- -`>> there was a lot of time spent , she acknowledges this, trying to grapple with the truth. she wanted to take the time to go back and make sure that she

>> sue klebold. dr. oz: were you ever scared of dylan? >> her biggest regret. dr. oz: do you think you were a good mother to dylan? >> could she have prevented the columbine tragedy? >> s sue: something went wrong in his thinking. >> sue klebold, what you haven't heard. dr. oz: if dylan were sitting in my seat, what would you want >> coming up next. dr. oz: today, a special edition of our show. columbine. a word that is synonymous with a tragic wave of school shootings that continue to plague our nation. columbine may still be the most notorious of them all. thanks to the meticulous and cold-blooded planning by dylan klebold and eric harris. imagine being the parent of one of those shooters. it's been 17 years since that infamous day in april. and for the first time, dylan klebold's mother, sue, is finally breaking her silence. this is a photograph of dylan klebold. at the time, he was 17 years old. and this photo from the same year. dylan on his way to the prom. can you see any signs that just three days later, he would participate in one of the worst school shooti