On April 20, 1999, Eric Harris and Dylan Klebold walked into Columbine High School carrying guns and homemade pipe bombs. Within an hour, 12 students and a teacher were dead and 24 others injured. Seventeen years later, Dylan’s mother Sue writes of a son she thought she knew in her new book “A Mother’s Reckoning.” Tonight on PBS NewsHour, Sue Klebold joins Jeffrey Brown to discuss her life in the shadow of tragedy. | PBS NewsHour