You need to contact your local US Department of Homeland Security office in Georgia (I believe the DHS in Atlanta covers your area) and contact their investigatory arm known as Homeland Security Investigations and report the below information to them. In all likelihood, you will be asked for evidence to support the allegation that your deceased brother's wife engaged in marriage fraud. You might yourself need to provide a declaration detailing your knowledge of the fraud. Marriage fraud is a serious immigration consequence as it establishes that an individual was not lawfully admitted for permanent residence. Engaging in marriage fraud not only can subject you to removal proceedings for violating immigration laws but it can also subject you to criminal charges. For assistance, you may want to contact a local immigration lawyer to provide guidance.
Answered on Jul 13th, 2012 at 2:26 PM