For which American Police Department did Detective Frank Serpico serve?

Francesco Vincent Serpico (born April 14, 1936) is a former New York City Police Department (NYPD) Detective who holds both American and Italian citizenship. He is known for whistleblowing on police corruption in the late 1960s and early 1970s, an act that prompted Mayor John V. Lindsay to appoint the landmark Knapp Commission to investigate the NYPD. Much of Serpico's fame came after the release of the 1973 film "Serpico", which was based on the book by Peter Maas and which starred Al Pacino in the title role, for which Pacino received an Oscar nomination.

Serpico was shot in the face whilst carrying out a drug raid. The bullet severed an auditory nerve, leaving him deaf in one ear, and he has since suffered from chronic pain from bullet fragments lodged in his brain.

The circumstances surrounding Serpico's shooting quickly came into question. Serpico, who was armed during the drug raid, had been shot only after briefly turning away from the suspect, when he realized that the two officers who had accompanied him to the hallway and door of the scene were not following him into the apartment or providing support and back-up. This raised the question whether Serpico had actually been brought to the apartment by his colleagues to be betrayed and murdered.