In 1982, Diaz was then involved in Operation Henry, an undercover investigation. Diaz and his partner worked with members of Scotland Yard in London in pursuit of a gang of British criminals who were involved in the sale and distribution of large quantities of heroin. During the course of this investigation, Diaz and his partner negotiated the sale of forty kilos of heroin with Ron Leslie, the principal subject. Leslie was responsible for the escape of Ronald Biggs from Wandsworth Prison. Biggs was one of the gang responsible for the 2.6 million pound Great Train Robbery in 1963. This case was the first time that DEA agents served as "agent provocateurs" for a country other than the United States. Subsequent to the arrest of Leslie, British authorities seized the 40 kilos of heroin. In 1986, Diaz was one of the principal undercover agents in Operation Pisces, an international operation involving Colombia and Panama. During the course of the investigation, Diaz laundered over 50 million dollars for members of the Medellin cartel including Jose Lopez and Alfonso Reyes, who were close associates of Pablo Escobar. Lopez and Reyes were subsequently arrested in a major dragnet which saw the arrest of over 350 defendants nationwide and the seizure of over 9 tons of cocaine and over 100 million dollars in cash and assets. According to the former U.S. Attorney General, Edwin Meese, Operation Pisces remains the largest most successful undercover drug investigation in the history of the United States. In 1988, the United States government, along with Victor Paz Estenssoro's government in Bolivia, launched Operation Blast Furnace, whose mission was to eradicate Bolivia's illegal coca producing fields and clandestine cocaine-producing laboratories located in the Chupari and Bene jungle regions. Diaz was a major participant. He flew 26 missions with the 210th combat air-wing out of Panama. Together with members of the 210th, he helped identify and destroy 16 clandestine cocaine laboratories. Diaz, whose nickname while in the DEA was "Louie the actor", embarked on an acting career after his days as a DEA agent were over. He chose the stage name "Lou Casal". He participated in over twenty major TV series, several Hollywood plays and movies. Diaz was featured in the documentary where he talked about growing up and how his relationship with his father influenced his life. His TV and movie credits are:   Theater:  Diaz wrote the book "Dancing with the Devil: Confessions of an Undercover Agent", published in 2010 by Simon and Schuster's digital book department.