Before April 20, 1999, Dylan Klebold existed in the same relative obscurity as any other high school student in America. Then, that day in April, he and fellow senior Eric Harris went on a shooting rampage at Columbine High School in Colorado that would change the face of the nation and inspire countless shooters (and even song lyrics) for generations to come. The two high school boys killed 12 people that day and injured 21 others before turning their weapons on themselves.

The Columbine shooting changed many lives forever, among them that of Dylan Klebold's mother, Sue. In 2009 Sue Klebold wrote a first-person article for Oprah Winfrey's O Magazine, but that was the only time she'd spoken regarding her son's actions—until now. Klebold gave her first-ever television interview Friday night, and today the Guardian ran an interview in which Klebold describes feeling an overwhelming sense of self-loathing for not spotting the signs her son was in distress.

"You go back over every conversation, every gift, every moment," she said. "I let this happen; it was my role to keep him safe, and to keep others safe, too, and somehow this happened because I wasn’t able to stop it. The guilt one feels doesn’t fit in a room, it’s so huge." She said she did notice a change in her son but "attributed it to being an adolescent," to her "deep regret." "If I had recognized that Dylan was experiencing some real mental distress, he would not have been there," she told Diane Sawyer in her interview for ABC. "He would've gotten help."

She and Dylan's father, Tom Klebold, were divorced after the massacre, and lawsuits filed by victims' families quickly bankrupted them. In her new book, A Mother’s Reckoning: Living in the Aftermath of the Columbine Tragedy, out February 15, Sue Klebold tries to come to terms with how Dylan, her "sunshine boy," became a sneeringly indifferent killer who held human life in such low regard. But despite the stain her son left on the country's history—and despite shootings such as those at Sandy Hook and Virginia Tech that were inspired by him—Klebold says she can't help but love him. "I didn’t have any choice," she said. "You love your children."

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