Castano commanded the United Self-Defense Forces of Colombia, known by the acronym AUC, in a mass grave in San Pedro, prosecutor Juan Pablo Hinestroza said Monday. Castano's remains were located after another former paramilitary leader gave the government the body's location.
Hinestroza said his office is "90 percent certain" the remains are that of Castano. A check of dental records will confirm the finding, Colombia Reports said.
Castano formed the militant group to protect his drug trafficking organization and farmers in the area from attacks by leftist groups that have been staging guerilla attacks on government forces for decades.
Castano's brothers were longtime allies of infamous Colombian drug kingpin Pablo Escobar though Castano's militants were longtime Escobar enemies.