BOGOTA, Colombia (Reuters) - Carlos Castano, who in the 1990s organized right-wing militias into a criminal army that terrorized Colombia, was murdered in 2004, police said on Monday after DNA tests proved they had recovered his remains. Guided by Castano's confessed assassin, who says he acted on orders from the victim's brother and fellow paramilitary founder Vicente Castano, Attorney General Mario Iguaran told reporters he was "99.99 percent sure" that bones recovered in northern Colombia were those of the late warlord. The investigation is part of President Alvaro Uribe's effort at ending Colombia's four-decade-old guerrilla war and could help pave the way for extradition of once-untouchable militia bosses to the United States on drug charges. Prosecutors say Vicente Castano ordered the murder because he feared his brother was about to spill information to U.S. agents about paramilitary cocaine smuggling operations. Vicente, who since Carlos' death has helped negotiate the disbanding of more than 31,000 militia fighters in a deal offering reduced prison sentences, is still at large. Also on Monday, Rodrigo Tovar, alias "Jorge 40," another top paramilitary leader, turned himself in as part of the demobilization deal. Tovar is accused of massacring peasants suspected of cooperating with Marxist rebels and of plotting to kill Hugo Chavez, the left-wing president of neighboring Venezuela. The paramilitaries were organized to combat the rebels, who have been at war with the state since 1964. U.S.-ally Uribe has been accused by human rights groups of giving soft treatment to the paramilitaries. Others say he is slowly negotiating them into a weaker position. Castano, Tovar and other militia leaders are wanted by Washington for cocaine smuggling. "Jorge 40's surrender and discovery of Carlos' remains means some of the truth is coming out and most paramilitary leaders are at least making a show of playing by the rules of the demobilization," said Colombian political commentator Ricardo Avila. "Both are helping the government strengthen its position to the point where a big name paramilitary leader will probably be extradited before the end of the year," he added.