Congressman Murtha was right to make an issue of this. The problem is not the crime--massacres happen in every war--but the coverup. The more quickly this is handled by a court-martial and the guilty punished, the better--because it would demonstrate that massacre is not US policy. US Marines are not professional baby killers, nor should they be, IMHO.
BTW, this might be a serious enough issue to force Rumsfeld's long-overdo resignation, if anyone has the nerve to take him on. How much worse can the image of America get? And it's been on his watch...