DOI is one of the oldest law-enforcement agencies in the country, formed in the 1870s following a scandal in which the corrupt William “Boss” Tweed and his unscrupulous cronies skimmed millions from the City coffers. Investigations may involve any agency, officer, elected official or employee of the City, as well as those who do business with or receive benefits from the City. As New York City's watchdog, DOI's strategy attacks corruption comprehensively through systemic investigations that lead to high-impact arrests, preventive controls and operational reforms that improve the way the City runs.