According to this July 2006 report, the GAO conducted an investigation testing whether radioactive sources could be smuggled across US borders. GAO purchased a small amount of radioactive sources and one secure container used to safely store and transport the material from a commercial source over the telephone. GAO's investigators, using counterfeit documents, were able to enter the United States with enough radioactive sources in the trunks of their vehicles to make two dirty bombs. GAO investigators were able to successfully represent themselves as employees of a fictitious company present a counterfeit bill of lading and a counterfeit NRC document during the secondary inspections at both locations. The CBP inspectors never questioned the authenticity of the investigators' counterfeit bill of lading or the counterfeit NRC document authorizing them to receive, acquire, possess, and transfer radioactive sources.