如果退美国籍了还用美国护照显然是犯了该坐大牢的重罪
看美国法典18 USC 911 和18 USC1541-1543等。 数罪并罚,可以蹲许多年
如果是根本没退籍,那显然是违反了中国的法律同样该坐中国的大牢
http://trac.syr.edu/laws/18/18USC00911.html18 USC Sec. 911
Whoever falsely and willfully represents himself to be a citizen
of the United States shall be fined under this title or imprisoned
not more than three years, or both.
http://trac.syr.edu/laws/18/18USC01543.html