The truth is that in this conflict you can never really know if a man is unarmed.
These terrorists and insurgents wear layers of robes that have hidden many a deadly bomb over the years. Perhaps this Marine may himself have lost friends to this treacherous brand of warfare. Our forces in Iraq are not fighting conventional forces and to try to fight them with conventional rules jeapordizes the lives of our fighting men.
1) non uniformed combatant- Illegal!
2) feigning injury or death in order to continue killing our soldiers
3) enaging in combat while in a house of worship- Illegal!
4) possibly a foreign national with no authority or protection under the Geneva Convention
5)just prior to this alleged shooting terrorists used the illegal tactic of wiring dead bodies with I.E. D. - at that specific point in the conflict, all rules of engagement were thrown out the freaking window!