The innocents were given the chance to get out and some of the big terrorists snuck out as innocent civilians. Big men, huh?
Plus, the Geneva Convention mainly deals with warfare between armies. The terrorists aren't an army, they represent no legal government in Iraq, they don't wear standard military uniforms, etc.
The solider was totally justified in that he was shooting an enemy terrorist who he thought was playing dead, who might have killed the solider and/or his fellow soliders. The terrorist didn't have his arms in the air in surrender, altough another terrorist did have his hands in the air and he was NOT shot.
Feel free to read this stuff. Maybe you have, but I'm sick and tired of hearing people that haven't read it act like they know what it says. It does apply to fighting an insurgencies.
Laws or Conventions like this aren't your enemy. In the long run it benefits you if there is a clear cut policy toward these things. If you don't something like this:
1) How do the soldiers know what they're allowed to do?
2) How can they get a fair trail if they are accused of war crimes?
3) How can we expect our enemies to adhere to some code?
If the GC and other agreements don't cover the situation, ok. Extend them, and put it in writing. What is the US policy on torture or torture-light? What are acceptable civilian casualties? It shouldn't be a secret.
The innocents were given the chance to get out...
"Attention Fallujah, would all innocent people please leave. All you terrorist stay right there so we can carpet bomb you." Fat chance of that working. Also, I could see an armed American in the situation wanting to stay behind and protect his house from looters. Is he still an innocent civilian?
This war is going to be worse for civilians than Vietnam, because the lack of vegetation will force the insurgents to hind in Urban areas amongst the population.
About this case: sure if the soldier feels threatened, it's all good. People accusing him say he did not act threatened; he wasn't trying to minimize exposure to a potential explosion. I don't know the details. Have a fair trial. If he's innocent, it will only discredit the human rights groups. Every now and then innocent people need to be put on trial. Not investigating this case would put the crediblity of the military on the line.