With less than two weeks left in Gov. Mark R. Warner's term, time is running out for him to arrange DNA testing that could determine whether Virginia sent an innocent man to the electric chair in 1992. If the tests show Roger Keith Coleman did not rape and murder his sister-in-law in 1981, it will mark the first time in the United States an executed person has been scientifically proved innocent, say death penalty opponents, who are keenly aware that such a result could have a powerful effect on public opinion. "I think it would be the final straw for...