After graduating from high school, Camarena joined the Marines. Following his discharge in 1970, he returned to Calexico and joined the police department. From regular police work, he moved on to undercover narcotics work as a Special Agent on the Imperial County Narcotic Task Force (ICNTF).
In response to strong American pressure, and to domestic law enforcement concerns, Mexico began eradication programs of opium and marijuana plantations, with large infusions of U.S. assistance. The first programs were on a smaller scale and used mostly manual eradication, such as "Operation Cooperation" in 1970. As plantation sizes grew, the eradication efforts also grew. In 1975, Mexican president Luis Echeverría approved "Operation Trizo", which used aerial surveillance and spraying of herbicides and defoliants from a fleet of dozens of planes and helicopters.