Reporting this to the INS is the best advice I can give. They would be the ones to investigate. It looks like fraud, from what you stated. But I do not know the whole story either. The website for the INS is:
USCIS Home Page
Their toll free number is:
If you have a question about immigration procedures, or need clarification, by calling our National Customer Service Center (NCSC)
at 1-800-375-5283 (TTY 1-800-767-1833). This toll-free call center has additional information and, during their specified office hours, can connect you to live assistance in English and Spanish. The NCSC will be able to answer most questions.