uscis has up to five years from the date of approval of greencard to rescind it if they thought you were not eligible for the benefit.
This is covered in the recission rules. This is not fraud but USCIS approving it by mistake.
http://uscis.gov/lpBin/lpext.dll/in....htm#slb-act246
INA: ACT 246 - RESCISSION OF ADJUSTMENT OF STATUS
Sec. 246. [8 U.S.C. 1256]
(a) If, at any time within five years after the status of a person has been otherwise adjusted under the provisions of section 245 or section 249 of this Act or any other provision of law to that of an alien lawfully admitted for permanent residence, it shall appear to the satisfaction of the Attorney General that the person was not in fact eligible for such adjustment of status, the Attorney General shall rescind the action taken granting an adjustment of status to such person and canceling removal in the case of such person if that occurred and the person shall thereupon be subject to all provisions of this Act to the same extent as if the adjustment of status had not been made. Nothing in this subsection shall require the Attorney General to rescind the alien's status prior to commencement of procedures to remove the alien under section 240, and an order of removal issued by an immigration judge shall be sufficient to rescind the alien's status.1/
This is covered in the recission rules. This is not fraud but USCIS approving it by mistake.
http://uscis.gov/lpBin/lpext.dll/in....htm#slb-act246
INA: ACT 246 - RESCISSION OF ADJUSTMENT OF STATUS
Sec. 246. [8 U.S.C. 1256]
(a) If, at any time within five years after the status of a person has been otherwise adjusted under the provisions of section 245 or section 249 of this Act or any other provision of law to that of an alien lawfully admitted for permanent residence, it shall appear to the satisfaction of the Attorney General that the person was not in fact eligible for such adjustment of status, the Attorney General shall rescind the action taken granting an adjustment of status to such person and canceling removal in the case of such person if that occurred and the person shall thereupon be subject to all provisions of this Act to the same extent as if the adjustment of status had not been made. Nothing in this subsection shall require the Attorney General to rescind the alien's status prior to commencement of procedures to remove the alien under section 240, and an order of removal issued by an immigration judge shall be sufficient to rescind the alien's status.1/