During the field investagation it should have been determined if the rounds entered the chest or the back of the Iraqis. That will shed some light on what really happened.
http://www.cnn.com/2005/LAW/04/26/marine.iraq.death.ap/index.html
http://www.cnn.com/2005/LAW/04/26/marine.iraq.death.ap/index.html