Hello - Lying about one's last name isn't usually a reason for deportation. Being here without legal status is, or being here as a permanent resident who committed certain serious crimes is also. But just lying about your last name is not.
There may be ways for your boyfriend to remain in the US, but you'll only know if you personally consult with an experienced immigration lawyer.
Good luck...
Daniel Shanfield
http://www.immigration-defense.com/
This information is for general information purposes only. Nothing here should be taken as legal advice for any individual case or situation. Each case is different, and the information provided herein does not constitute a prediction or guarantee of success or failure in any other case. This information is not intended to create, and receipt or viewing of this information does not constitute, an attorney-client relationship.
Answered on May 21st, 2014 at 1:14 PM