"DEA officials state that without confidential sources, the DEA could not effectively enforce the controlled substances laws of the United States. Confidential sources come from all walks of life and are significant to initiating investigations and providing information or services to facilitate arrests and seizures of drugs and cash. According to the DEA, it has approximately 4,000 active confidential sources at any one time."

Source

Office of the Inspector General, Audit Division, "Executive Summary: The Drug Enforcement Administration's Payments to Confidential Sources," (Washington, DC: U.S. Department of Justice, 2005), p. 1
http://www.justice.gov/oig/re…