First, the FBI is late to the game. “Some of the witnesses have already been interviewed by the Iraqi government and some already have said what they want to say in the media. That’s a problem,” said Carter, a government contracts and international law attorney in McKenna’s Los Angeles office.

Second, he said, Iraqis are generally reluctant to interact with Americans because they fear being kidnapped or killed by retaliating insurgents. Third, it will be nearly impossible to reconstruct the scene or collect any physical evidence given the passage of time. Fourth, “just the sheer confusion of the battlefield,” Carter said, makes eyewitness testimony — American or Iraqi — so unreliable.