Am I mistaken, or was Atta actually an American citizen? I thought all this time that he was an alien on a visa.
The regulations refer to US persons, which aparently includes legal resident aliens, either permanent or temporary. They thought Atta was legal, but in reality he wasn't. I didn't say the regulations made sense, nor the court rulings they are based on, which give most Constitutional protections to legal and even illegal aliens.
"Am I mistaken, or was Atta actually an American citizen? I thought all this time that he was an alien on a visa."
you are correct.