Alex Haley's Roots got her started. When she first read that epic reconstruction of a black family's odyssey from freedom in Africa to slavery and emancipation in Virginia, Dorothy Spruill Redford could trace her family only as far back as her grandparents. But Haley's genealogical pilgrimage impelled her to one of her own. For Redford, 43, a brisk, hard-driving welfare department supervisor in Portsmouth, Va., the quest would last a decade and grow into an obsession, an irresistible desire to light up the dark past.
Redford's off-duty hours and vacations turned into a blur of musty documents and marathon interviews of...