Javier Contreras was a Guadalajara Cartel associate during the 1980s. In 1984, DEA agent Kiki Camarena recruited Contreras as a paid informant, and, one day, Camarena brought Mexican policeman Guillermo Calderoni (whom he introduced as fellow DEA agent "Jorge" from Dallas) and asked Contreras where Rafael Caro Quintero was. Contreras hesitated until Calderoni pinned him against a wall and brutally beat him, aiming a gun at him and forcing him to reveal that he was rumored to be in the Tierra Blanca neighborhood. Calderoni then shoved him to the floor and left, and an infuriated Camarena criticized Calderoni for ruining one of his informants.