Last month the Food and Drug Administration warned 19 doctors and clinics that counterfeit vials of the chemotherapy drug Avastin had been identified in the U.S. Most of those doctors were in California. Today the Wall Street Journal reports that the FDA is investigating two businessmen from Canada who may be the source of these vials. One of them had admitted to shipping fake Avastin last year, although he says he did not know the vials contained counterfeit drugs. While it is generally illegal for anyone but the manufacturer to import prescription drugs into the U.S., it happens frequently and has proven difficult to police, the Journal reports.