When you need the documents and the explosives, after you hear the Allied prisoner get shot, move out of the building. Go up the stairs by the truck, make a left, and follow the path (it is actually a guide rail). You must fight some enemies along the way. When you make it to the room, you will see a man being tortured by another man. Be careful; there is another man hiding. Also make sure to shoot him. After you kill the two soldiers, the man will say "You saved my life sir" and will become part of your regiment. Note: If you do not do this after you get the documents and the explosives, Major Grillo will die every time. This will not work all the time.