"They would drive them here and turn down this track," Alexandra Reznikova said as she hiked into the woods deep within this military preserve northeast of St. Petersburg. "Then they would bring them here, to the trenches," she said, making her way through the birch trees and pines. "Maybe soldiers dug them. Maybe they had to dig their own graves." Here in these woods, accompanied by the frequent rumble of artillery barrages, Reznikova and a team of researchers from the human rights organization Memorial have unearthed what they say is grim evidence of one of the Soviet Union's most egregious...