i guess innertube only has the newest season, and only for a few weeks. i dont have itunes but i know you can buy csi episodes there. maybe someone who has dealt with itunes can tell you what episodes are available. these two methods are the only legal ways to see csi episodes without the dvds and are so the only ones allowed to be discussed on the board.
as to why csi investigated the death of a marine, probably thats just the story they wanted to do. maybe they were hoping no one would notice. *shrugs* i dont know about the states but are agencies like ncis and whatever the one for the army was called not found everywhere? maybe they dont have access to that kind of thing in new york or miami so the regular police department handled it.