The teenage boy charged with murdering eight students and two teachers during a gun rampage at a Houston-area high school on Friday studied previous mass shootings before carrying out his attack, sources told ABC News. The accused killer, Dimitrios Pagourtzis, 17, “used aspects of those attacks in his own shooting,” a source said. Classmates at the school in Santa Fe, Texas described Pagourtzis as a quiet loner who played on the football team.