NEW : May 12 U.S. hearing in Russia postponed . A boy adopted by a Tennessee family is back in a Russian prison . He was sent back to Moscow alone in April . A U.S. Senate hearing on Russia is scheduled in the case next week .
NEW : August 12 U.S. hearing in case postponed . A boy adopted by a Tennessee family is back in a Russian orphanage . He was sent back to Moscow alone in April . A U.S. court hearing on guardianship is scheduled in the case next month .