Diego Fernando Murillo Bejarano was born on February 23, 1961, in Colombia. Little is publicly reported about his early childhood or family life before he entered the world of organized crime. Murillo became involved in criminal activities as a young adult, joining a squad that targeted drug lords and criminal rivals. After a botched operation resulted in the death of his associates, Murillo narrowly escaped and fled to the city of Itagüí, where he established ties with the influential Galeano family, prominent figures in the Medellín Cartel and controllers of the Oficina de Envigado criminal network. During this period, Murillo suffered a gunshot wound that left him with a permanent limp, a physical mark he carried for the rest of his life.

After the assassination of the Galeano family on the orders of Pablo Escobar in 1992, Murillo survived and shifted alliances to Los Pepes, a vigilante group formed by rivals of Escobar and led by the Castaño brothers. Through this group, Murillo seized control of the Oficina de Envigado and expanded his influence in Medellín’s underworld. By the late 1990s, he was a leading figure in both the criminal underworld and paramilitary organizations, working closely with the Castaño brothers and leading paramilitary blocs such as Cacique Nutibara and Granada Heroes. His rise coincided with widespread violence and turf wars among rival gangs, culminating in his control over much of Medellín's drug trafficking and contract killing operations. As his power grew, Murillo became known as one of the most feared and influential underworld bosses in Colombia.

Murillo’s criminal career was marked by his involvement in drug trafficking, kidnapping, extortion, and paramilitary violence. As a key leader of the Oficina de Envigado, he oversaw numerous criminal activities, including the organization of hitmen, drug distribution, and the management of illegal enterprises previously controlled by the Galeano family. His influence expanded as he took command of powerful paramilitary blocs within the United Self-Defense Forces of Colombia (AUC), rising to third in command of the organization and becoming a central figure in negotiations with the Colombian government during the 2003 peace process at Santa Fe de Ralito.

Despite his public demobilization in November 2003, Murillo continued to be linked to criminal activities. In 2005, he was accused in court of orchestrating the murder of a local deputy, prompting him to flee the demobilization zone, though he surrendered to authorities a few days later. Murillo and his associates were detained but continued to wield significant influence from prison.

On May 13, 2008, Murillo and 13 other paramilitary leaders were extradited in a surprise move by the Colombian government to the United States, on charges of drug trafficking and money laundering. Critics argued that extradition would shield Murillo from prosecution for more severe crimes committed in Colombia, such as murders and human rights abuses. On June 17, 2008, he pleaded guilty in U.S. federal court to trafficking multiple tons of cocaine. He was sentenced on April 22, 2009, to 376 months (31 years and 4 months) in prison and fined $4 million. His extradition drew protests from victim organizations and human rights groups, who argued that it undermined efforts to achieve full truth and justice for the victims of paramilitary violence. As of 2025, Murillo remains imprisoned in the United States, with calls ongoing for his return to Colombia to face justice for his crimes there.