She has spoken only a few times to the media in the past, but has never appeared on television. Her first TV interview, given to ABC's Diane Sawyer, aired Friday night.
In it she talks about what life has been like after April 20, 1999, when her son, Dylan Klebold, and schoolmate Eric Harris committed what is the deadliest high school shooting in U.S. history. Clad in black trenchcoats and wielding four guns, the pair worked their way through the Colorado school after their plan to blow up hundreds of classmates failed.
Images of terrified students being led from the school with their hands on their heads became ingrained in national memory.
Sue Klebold never thought her son would do anything so horrific.
"I had all those illusions that everything was OK because, and more than anything else, because my love for him was so strong," she says in the interview, according to a snippet released Thursday.
When her discussion with Sawyer turns to how many other parents insist they would have seen warning signs and been able to prevent the shootings, she says, "Before Columbine happened I would have been one of those parents."
"If I had recognized that Dylan was experiencing some real mental distress, he would not have been there," she says. " 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."
In a 2009 essay for O magazine
, Klebold wrote that her son had a fun childhood but when he became a teenager things changed. She just didn't think the worst, though. She wrote in O that she thought her maternal instincts would keep him safe. She would know if there was trouble.
She tells Sawyer that one of the things that has haunted her has been the thoughts she has almost every day about the children and the teacher who needlessly died.
"I just remember sitting there and reading about them," she says while holding back tears, "... all these kids and the teacher. ... and I keep thinking, (have) 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."
She has said previously that she and her husband don't understand why their son took part in the massacre.
One of the survivors of the massacre wrote a Facebook post directed to the mother.
Anne Marie Hochhalter was paralyzed after being shot.
She said she has no ill will toward Sue Klebold and wouldn't judge her for the actions of others.
"I have forgiven you and only wish you the best," Hochhalter wrote
Hochhalter said that she was touched by a lengthy letter she received from the Klebolds a few months after the shooting.
A cautionary tale for parents
Klebold hopes her story, which she tells in a book to be released next week
, will help other parents spot potential signs of trouble with their children.
Dylan Klebold was 17 when he and Harris,18, carried out their long-planned attack on the high school about 13 miles south of downtown Denver. After 49 minutes in which they killed 13 and injured 24 others, they each committed suicide.
The death toll could have been much, much worse; homemade propane bombs left in a cafeteria where hundreds of students were eating lunch failed to go off. Neither did bombs planted in their cars that were designed to kill people who responded to the scene.
"I wish I had known then what I know now: that it was possible for everything to seem fine with him when it was not, and that behaviors I mistook as normal for a moody teenager were actually subtle signs of psychological deterioration," Sue Klebold wrote on the website for her book.
In his junior year, Dylan hacked the school computer system, she said. He scratched some hateful words on a kid's locker and he and others broke into a van and got arrested.
"He acted cold, like he had done nothing wrong." She and the father lectured him, took away privileges. Meanwhile, he was writing in his journal that he wanted to get a gun. She confronted him one night and gave him "the old mom lecture. And I said, 'By the way it's Mother's Day and you forgot it. ... He said, 'Mom don't push me.' "
He went out and bought a little gift and she thought everything was fine.
In the O essay, she talked about raising Dylan.
" I taught him how to protect himself from a host of dangers: lightning, snake bites, head injuries, skin cancer, smoking, drinking, sexually transmitted diseases, drug addiction, reckless driving, even carbon monoxide poisoning. It never occurred to me that the gravest danger -- to him and, as it turned out, to so many others -- might come from within. Most of us do not see suicidal thinking as the health threat that it is. We are not trained to identify it in others, to help others appropriately, or to respond in a healthy way if we have these feelings ourselves."
Klebold will donate the profits from her book to charities devoted to mental health issues, her publisher said.