http://www.usdoj.gov/ndic/srs/20469/index.htm
"Overview - Clandestinely produced fentanyl has been linked to hundreds of fatal and nonfatal overdoses across the Midwest, Northeast, and Mid-Atlantic Regions of the United States since late 2005. Fentanyl is a synthetic opiate approximately 50 times more potent than heroin. From 1990 through 2005 at least nine clandestine fentanyl laboratories were seized in the United States; however, sensitive intelligence related to ongoing law enforcement operations indicates that Mexico likely is the source of the fentanyl associated with these recent overdoses. In May 2006 Mexican law enforcement authorities seized a fentanyl laboratory in Toluca, Mexico. In February 2006 U.S. Customs and Border Protection (CBP) agents seized a wholesale shipment of fentanyl powder just north of the U.S.-Mexico border."
