The study involved reviewing court records and interviewing investigators and their supervisors in four jurisdictions: Broward County, Florida; Arlington County, Virginia; Baltimore, Maryland; and Phoenix, Arizona. All case analysis was conducted between 1985 and 1988. Researchers reviewed 20 closed drug trafficking cases in each jurisdiction that had resulted in conviction, 10 cases made exclusively by local police and 10 brought by the Drug Enforcement Administration (DEA). Most DEA cases involved wholesalers who operated at the higher end of the drug distribution chain. Researchers looked at the managerial and psychological weaknesses of drug wholesalers and their economic vulnerabilities. With respect to investigative techniques, it was found that informants were central to the development of cases involving consensual crimes. Most cases in the four jurisdictions were made on the basis of informant testimony that helped undercover investigators arrange purchases of drugs from wholesalers or their employees. Asset seizure and forfeiture programs were prominent only in Broward County and Baltimore. Electronic surveillance was used infrequently in the four jurisdictions, with the exception of cooperative local and Federal investigations in Baltimore. Challenges that police officers face with respect to heroin and cocaine markets are discussed, along with the organization of drug wholesaling operations. Recommendations to help local law enforcement agencies deal with drug traffickers are offered. Appendixes note the resources of narcotics units in the four jurisdictions and the questions used to interview and analyze DEA cases. 4 references