DOI also investigates the backgrounds of persons selected to work in decision-making or sensitive City jobs, and conducts checks on companies and their principals to help agencies determine if they are companies that can be awarded City contracts.

DOI can forward its findings to federal and state prosecutors, which can result in arrests.

It can also refer its findings to the City's Conflicts of Interest Board, and other agencies who make disciplinary or other administrative decisions.

[5] Though most of its investigations occur within New York City or the surrounding areas, DOI may inquire about activities that occurred outside of New York when such activity is related to DOI's subject matter jurisdiction.

[8] The DOI was founded in 1873 as the Office of the Commissioners of Accounts as a result of the Boss Tweed and Tammany Hall scandals.