For years, countless migrants have risked everything trying to cross the U.S.-Mexico border. But some never make it and meet a tragic ending. A number of those who die during the journey do not carry ID. But there is a group of scientists devoted to identifying the nameless. They also help bring closure to their grieving families.  Correspondent John Zarrella –who traveled to Texas to meet these dedicated forensic anthropologists- shares with Elaine Reyes the insights of this story of hope, humanity and science.