Fidel Castaño Gil was a Colombian paramilitary leader and drug trafficker who led the ACCU and later the ACU against left-wing guerrillas in the Colombian jungle. He was one of the founders of the Los Pepes death squad, which acted against the Medellín cartel.
In the late 1970s, his wealthy father was kidnapped and murdered by the left-wing guerrilla movement FARC after Fidel and his brother Carlos failed to pay the ransom. Enraged by their father's death, the brothers formed the Autodefensas, a right-wing paramilitary to extract revenge. With CIA funding and training, the autodefensas became a feared paramilitary group in the Colombian jungles, infamous for their war crimes; including killing villagers living in areas with FARC presence.
In 1992, their CIA associate Bill Stechner convinced them to enter an alliance of drug traffickers against Medellín cartel leader Pablo Escobar. The brothers, detesting Escobar for his collaboration with leftist guerrilla M-19 years ago agreed, and convinced Escobar's rivals Judy Moncada and the Cali cartel to fund Los Pepes, a paramilitary group of Escobar's rivals. With the Cali cartel's finances and indirect help from DEA agent Javier Peña, the Los Pepes succeeded in killing several of Escobar's associates, including Escobar's brother-in-law Carlos Henao. After Escobar's death at the hands of the Search Bloc in December 1993, the Los Pepes laid down their weapons. Gilberto Rodríguez Orejuela, the leader of the Cali cartel, thanked the brothers for their help by giving them the location of Judy Moncada's laboratories, inviting them to the cocaine business. The brothers accepted the invitation, and entrusted the help of Escobar's former head-of-security Diego Murillo Bejarano for their cocaine trafficking enterprise.
He disappeared in 1994 and confirmed dead years later, his death has been subject of heavy speculation, some say he was killed in combat by communist guerrillas, other sources say that his brother Carlos ordered his death because of boiling tensions between them involving women, death of relatives and control over the AUC.