A high school teacher is allegedly on the run with a 15-year-old female student and investigators warn he is armed and dangerous. Elizabeth Thomas was last seen stepping into Tad Cummins’ SUV at a Columbia, Tennessee gas station Monday. A nationwide Amber Alert was issued when police determined the teen was in extreme danger. Cummins lost his teaching job last month amid accusations about his close relationship to his student. Nancy Grace and Alan Duke take a close look at the investigation in this episode.