The former principal of Columbine High School says he recites the names of 13 victims who were killed in the tragedy every morning. Frank DeAngelis, known to his students as “Mr. De,” was the principal at Columbine High School when the massacre took place 20 years ago this week. Now retired after 35 years at Columbine, he has written a book, "They Call Me 'Mr. De': The Story of Columbine's Heart, Resilience and Recovery." All proceeds go to charity.