Person of Interest: Seasons 1-5 (2011-2016)

A computer genius named Finch developed a machine for the government that is used to detect information leading to acts of terrorism before they happen. The machine separates the information gathered into two categories: relevant and irrelevant. Finch, however, discovered that the irrelevant information often led to other acts of violent crime. So, he, before going underground, developed a back door into the system which only spits out the social security number of a central person involved in the crime. Supposedly dead in the authority's eyes, Finch hires John Reese, an ex-CIA special operations agent, who, too, dropped out of life after his girlfriend was killed as the result of a professional incident, and he was dissatisfied with the government's handling of the situation.