An inquisitor was an official (usually with judicial or investigative functions) in an inquisition – an organization or program intended to eliminate heresy and other things contrary to the doctrine or teachings of the Catholic faith. Literally, an inquisitor is one who "searches out" or "inquires" (Latin inquirere < quaerere, 'to seek'). In some cases, inquisitors sought out the social networks that people used to spread heresy. There were multiple national inquisitions with different approaches and targets. Source: Wikipedia (en)