Why ?
Is there some dispute that the case IS about a Marine sergeant whose squad killed 24 Iraqi men, women and children ?
This is the same bogus biased and incendiary garbage the leftist nosepickers always run in the first paragraph of Haditha stories.
To answer your question, this case and everything surrounding it since the "Haditha Massacre" meme was hatched, is about far more than 25 deaths.
Here's a link to a good place to start...
http://warchronicle.com/TheyAreNotKillers/DefendOurMarines/TopicIndex/EvidenceRoom.htm