Eric Harris and Dylan Klebold walked into Columbine High School in April 1999 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.” Sue Klebold joins Jeffrey Brown to discuss her life in the shadow of tragedy.