I knew u'd say that... but I agree may be not for the same reasons, what r ur motives?
Mine

1. The investigation should determine whether or not he's an enemy combatant  If it is possible to establish that he was engaged in a conspiracy to kill citizens or related activities at the time he solemnly swore on the Constitution to acquire the Citizenship, he may be declared an enemy combatant.
2. There can't be any profit to acquire the Citizenship to commit a terrorist act

Any doubt should benefit the enemy combatant status for the suspect since any signal that Citizenship can be a legal shelter to commit a terrorist act would send the wrong message and cause a very legitimate public outrage.