It occurred to me while reading this thread that if this person had been treated as a POW, rather than as a carefully non-categorized non-person, he would still be - perfectly legitimately - in custody, rather than wherever he is after having successfully perpetrated a suicide attack in Iraq. The nice thing about POW status (at least in my layman's understanding) is that you don't have to prove that the detainee committed a crime in order to continue to detain him until the hostilities in which he was involved cease. We can't torture him, of course, which is a bummer to some; but we can keep him in custody until hostilities are definitively over.
If it turns out that he is a criminal, at least as I understand it he can be turned over to the proper authorities when that comes to light. And his treatment as a POW, unlike extra-legal treatment as an 'illegal combatant', will not interfere with prosecution or lead to premature release.
It further occurred to me that that - his status as an indefinitely yet legally and morally imprisoned POW, had it been the case - would probably represent an intolerable outrage to both the anti-war Left and the pro-war Right.