This dissertation investigates denunciation practices within the Spanish Inquisition district of Cartagena de Indias during the Seventeenth century. Through a detailed analysis of archival records pertaining to religious persecution by Cartagena's tribunal, it elucidates how denouncers actively shaped and influenced the Inquisition's operational scope, often serving as the primary catalysts behind its prosecutorial endeavors. It also reconstructs the evolution of prosecutorial activities in Cartagena’s district during the Habsburg period and delineates the social profiles of the prosecuted individuals. The research argues that denouncers were not merely passive informants but active agents who significantly influenced the trajectory of religious persecution in the region. By shedding light on the actions and motivations of denouncers, this study contributes to a deeper comprehension of the broader dynamics of the exercise of power and authority within the context of the Spanish Inquisition in particular, and in the Spanish Atlantic empire in a broader sense.