The blood stains on the wall don't fit with the way the men are lying in the pit they were found in. If they were stood against the wall they wouldn't have been lying flat on their backs in the bottom of the pit. There wasn't room for their killers to be in the pit with them, so they would have had to have been well above their victims when they killed them. That, too, would have changed where the blood stains on the walls were, but the bodies still would have fallen in a heap on the floor not been neatly laid out. And even if they were told to lie on the floor before being shot, there wouldn't have been any stains on the walls.