Though he demobilized in 1991 at the age of 19 along with some 2,500 other EPL members, he returned to fighting only a few months later with his brother, Juan de Dios Usuga, alias "Giovanni."
Usuga later began associating with right-wing paramilitary groups. He is accused of having participated in the 1997 massacre in Mapiripan, Meta, with the United Self-Defense Forces of Colombia (AUC) when the Castaño brothers sent a team of fighters to the Eastern Plains to begin a war campaign against alleged guerrillas and killed dozens of suspected rebel supporters.
At some point during his time with the AUC, Usuga joined his brother Giovanni in working for drug trafficker Daniel Rendon Herrera, alias "Don Mario," as part of the AUC's Centauros Bloc, laundering funds and handling extortion payments. He again surrendered arms, this time under the AUC's demobilization process in 2005. However, this demobilization was also short lived and he soon reuinted with Don Mario to help form the Urabeños.
After Don Mario's capture by Colombian authorities in 2009, Otoniel and his brother assumed complete control of the Urabeños. There are some rumors that Usuga tipped off the security forces, leading to Don Mario's capture.
Since then, he and his brother greatly expanded the Urabeños' operations in Uraba, a territory long prized by drug traffickers given its access to the Caribbean and Pacific coasts, as well as making push into the Eastern Plains and the Rastrojos stronghold of Valle del Cauca province on Colombia's Pacific coast.
Following Giovanni's death at the hands of Colombian security forces in January 2012, Giovanni is now the supreme leader of the Urabeños. He was indicted by the Southern District of New York in 2009, with the US State Department offering $5 million for information leading to his arrest.
US Department of Treasury, Office of Foreign Assets Control: Kingpin Act Designations (March 2010)
US State Department, "Narcotics Rewards Program: Dario Antonio Usuga David"
"Quien es alias Otoniel, el jefe de la temida banda criminal 'los Urabeños'?" El Pais, November 26, 2012