The story isn't about that. Murtha is simply using the story.
Murtha's gross accusations of "cold blooded" murder has more than fueled the story to above the fold news across the globe. Until then it was a quiet investigation, by MSM standards. This is not just a story about what happened, its a story about jumping the gun, innocence until proven guilty, quagmires, and the whole enchilada in Iraq. That is how the MSM is framing it, with hundreds and hundreds of stories.
I would be MORE than suprised if 1/10th of the accusations are true (putting kids in the room and tossing in grenades, shooting an old wheelchair bound man in the chest, shooting kneeling women at point blank range). Sounds to me the jihadis are overplaying their hand.