Well into her nineties, Rosa Coscollá still remembered with perfect clarity the day that two policemen entered her house and took away her father. The year was 1939, near the end of the Spanish Civil War. She was just 15 at the time, living in the rural town of Xeraco, south of the city of Valencia.

When she saw her father for the next and last time, he was in jail—badly wounded, malnourished, a political prisoner. Vicente Coscollá Ibáñez was soon executed, and Rosa spent the rest of her life hoping for the day when DNA samples would be obtained from the mass grave to confirm where her father was supposedly buried.

"In her final years, she was obsessed with her father's