The USS Beleau Woods was named for a WW1 battle in which the US Marines fought the Germans in a place called Beleau Woods. There are many reasons why persons might be listed as MIA. It would be possible for someone to be wounded seriously enough so as not to be able to speak. If their ID tags were lost, then it would be hard, if not impossible, to identify them. In the meantime, they would probably be declared MIA by their unit. If they were able to identify themselves later & then died, they would be removed from the MIA list & be listed as KIA. It sounds cold, but terrible things happen in war.