"[3] A recently promoted police inspector, nicknamed "Il Dottore" ("the Doctor", an Italian honorific) kills his mistress, and then covers up his involvement in the crime.

He insinuates himself into the investigation, planting clues to steer his subordinate officers toward a series of other suspects, including the woman's gay husband and a student leftist radical.

His personal neurosis caused by his extreme position of power, and his firm beliefs in the role of authority, eventually drive him to try to accuse himself with every possible evidence.

The New York Times called the film "a suspense melodrama with the moral concerns of angry satire [...] When it opened in Italy early this year (and later, when it was shown at Cannes), Investigation was hailed for the ways in which it exposed the corrupt, authoritarian practices of the police, who place themselves above their own laws [...] The story moves forward with a relentless momentum.

[7] David Fear of Time Out called it "[a] paranoid police procedural, a perverse parable about the corrupting elements of power, and a candidate for the greatest predated Patriot Act movie ever [...]".

[12] The Cannon Group had hoped to remake the original film with Andrei Konchalovsky (of Runaway Train fame) attached to direct.