Rose Gill Hearn has served as the Commissioner of the Department of Investigation since inception of the Bloomberg Administration in 2002 and is the longest serving DOI Commissioner.

Since DOI's creation after the "Boss" Tweed and Tammany Hall scandal, the agency's scope and importance have grown. The agency serves as the City’s municipal watchdog with oversight of more than 300,000 City employees in 45 City agencies; dozens of Boards and Commissions; the Office of the Inspector General for the New York City Housing Authority, the largest housing authority in the country; the Office of the Special Commissioner of Investigation for the New York City School District, which monitors the Department of Education's 135,000 employees; and the Office of the Inspector General for the Housing Development Corporation, a unit created during Commissioner Gill Hearn’s tenure. 

Since her appointment, Commissioner Gill Hearn has spearheaded and presided over numerous successful investigations, including one that led to criminal charges against 11 defendants and a corporation in a multimillion-dollar kickback and fraud scheme involving the City's automated payroll system and which also resulted in a $500 million payment by the project’s prime contractor, with most of those funds returned to the City in compensation for fraudulent overcharges; the arrests of 18 tax assessors for taking bribes; the indictment of a New York City Councilman who extorted a real estate developer seeking City approval to build a multi-million dollar waterfront development project in Brooklyn; the arrests of 19 Department of Buildings’ plumbing inspectors for bribery; the indictment of a high-ranking Department of Correction official for Grand Larceny; and the indictment of the former President of the Housing Development Corporation for siphoning agency funds for personal expenses as well as receiving child pornography. She has also overseen the agency's investigations into several high-profile public corruption cases that resulted in the arrests of public officials.

Under Commissioner Gill Hearn’s leadership, DOI has established many innovative initiatives that have raised the agency’s profile, increased the number of tips to DOI and resulted in record-high arrest numbers. These initiatives include: corruption prevention awareness lectures presented to City agencies and contractors, Compstat, proactive monitors to oversee several major infrastructure projects, technology to receive online complaints, the Tort Fraud Task Force that ferrets out phony claims against the City, and the creation of new units such as the Computer Forensic Unit and the Not-for-Profit / Vendor Fraud Unit.  Commissioner Gill Hearn also instituted a prevention program whereby agencies receive a written advisory regarding any vulnerability in agency operations exposed by a DOI investigation. DOI follows up to make sure the problem is corrected to prevent recurrence.

Commissioner Gill Hearn has guided DOI to become a national and international model for municipal corruption fighting. Following publicized scandals in the city of Chicago, Commissioner Gill Hearn met with Mayor Richard M. Daley and his commissioners to aid the Chicago Inspector General Office's effort to strengthen its authority. In addition, she brought DOI's work to a global audience, presenting the agency's mission at a 2007 world cities conference on public integrity in Amsterdam. She contributed a chapter to the book, Local Integrity Systems: World Cities Fighting Corruption, which documented the findings from the Amsterdam conference. In October 2008, DOI hosted the first New York City National Watchdog Conference, bringing together scholars on integrity issues with Inspectors General from around the country to discuss and debate the issues that anti-corruption agencies face.

Prior to her appointment, Commissioner Gill Hearn was Deputy Chief of the Criminal Division in the United States Attorney’s Office for the Southern District of New York. Her successful trials of fraud, theft, narcotics and money laundering earned awards from the Federal Bureau of Investigation, Drug Enforcement Administration, New York City Police Department, U.S. Secret Service and U.S. Postal Inspection Service. She has also taught Trial Advocacy as an Adjunct Professor of Law at Fordham Law School and served as a litigation associate at Lord, Day & Lord, Barrett Smith in New York.

Commissioner Gill Hearn is a 1984 graduate of Marymount Manhattan College and a 1988 graduate of Fordham University School of Law, where she earned numerous honors, including the Ethics Award.