holocaust memorial museum, who also sits on yahad's scientific board. >> paul shapiro: the method that he's used, extraordinary. we can understand minute by minute what happened in hundreds of localities where before we just had fog. >> logan: how reliable is his work? >> shapiro: he has opened the door to the use of multiple sources to understand what really happened on the ground in a big part of europe. >> desbois: the babies were shot, too. >> logan: we found father desbois a cautious and skeptical interviewer. >> dimitri ( translated ): when a woman with a baby would approach the pit, they forced her to hold the baby in sight. first, they shot the baby and then her. >> logan: he never judged or showed emotion as he listened to the darkest accounts of humanity. father desbois insists that every killing site they find is memorialized by recording the gps coordinates. they never physically mark the graves because, he says, people would loot them. father desbois believes, when his work is finished, the number of jewish victims will total more than has been previously documented. but t