Iván Roberto Duque Gaviria aka Ernesto Báez (May 9, 1955 – November 19, 2019) was a Colombian paramilitary leader and onetime member of the demobilized United Self-Defense Forces of Colombia (AUC).
He was democratically elected as Mayor of the municipality of La Merced and later worked for the Empresas Públicas de Manizales.
In 1982 founded the Asociación Campesina de Ganaderos y Agricultores del Magdalena Medio, ACDEGAM (Ranchers and Farmers of the Middle Magdalena Peasant Association) in Puerto Boyaca presumably as a facade for the creation of paramilitary groups in the troubled region.
He was arrested and imprisoned at La Modelo Maximum Security Prison under assassination and confirmation of illegal paramilitary groups charges.
Baez disliked how Castaño became the de facto speaker of the organization, and also had differences with another paramilitary and his affinities with Castaño, known by the alias of "Doble Cero" commander of the Metro Bloc, after the killing of two members of the BCB in 2002 in an internal cleansing.