The mother of Dylan Klebold, one of two boys who killed 13 people at Columbine High School in 1999, gave her first televised interview Friday. Speaking to ABC's Diane Sawyer, Sue Klebold said she missed warning signs her son was depressed. "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 him from hurting other people," she said. Klebold's interview, which you can watch here, comes as she promotes her Feb.