Investigating dealers of counterfeit drugs is similar to investigating drug cartels, Pfizer has found. It's easy for detectives to jump out and catch the guys selling pills on the corner. It's much harder to catch the kingpins. There's one big difference, though. With cocaine, say, the whole supply chain"”from farming to retailing"”tends to be run by one cartel. With fake pharmaceuticals, the marketplace is open and alliances are constantly shifting. To get to the source, detectives typically start with small-time retailers and work their way up the supply chain.