Christian J. Klossner

Christian J. Klossner is the Executive Director of the Office of Special Enforcement (OSE). He previously served for over five years as the deputy director of the District of Columbia's Office of Police Complaints (OPC), where he oversaw the agency's investigative, adjudication, mediation, outreach, and administrative activities. Prior to joining OPC, he worked as an assistant district attorney in the Office of the Special Narcotics Prosecutor of New York City and the Office of the Bronx District Attorney. He also served as an adjunct professor of trial advocacy at his alma mater, Fordham University School of Law. Before earning his J.D. from Fordham, Mr. Klossner worked as a campaign organizer, lobbyist, and staff supervisor with the New York Public Interest Research Group.

Francine Vlantes O'Keeffe

Francine Vlantes O'Keeffe is the Deputy Executive Director of the Office of Special Enforcement (OSE).  She previously served as Special Assistant Corporation Counsel for OSE, where she investigated and brought legal action to stop residential buildings from being used for illegal short-term rentals.  Prior to joining OSE, she served as a hearing officer with the Office of Administrative Trial and Hearings (OATH), where she presided over administrative adjudications of alleged violations of city laws and rules affecting public safety and health.  She also served as a federal judicial law clerk to the Honorable Freda L. Wolfson, now Chief Judge for the United States District Court, District of New Jersey.  Prior to entering public service, she was an associate at Lowenstein Sandler practicing white-collar criminal defense and business and class action litigation.  Ms. O'Keeffe received both her undergraduate and law degrees from Rutgers University.

Aditi Sen

Aditi Sen serves as a Special Advisor in Policy and Research, leading the data analytics and strategic campaign work for the office. Prior to joining OSE, she was a research analyst at the Center for Popular Democracy, producing research studies to support a wide range of state and local policy campaigns by community organizations nationwide, on issues such as housing affordability, fair scheduling initiatives, and education policy. Before CPD, she worked at SEIU Local 32BJ, where she used data analysis and strategic research to shape the union's worker organizing efforts in the residential real estate industry within New York City. Ms. Sen holds a Bachelor of Arts in Social Studies from Harvard College and a Master of Regional Planning from Cornell University.

Eryn DeFontes

Eryn DeFontes is the Investigations Coordinator. Prior to her tenure at OSE, Ms. DeFontes served as the Deputy Director of the Labor Law/Prevailing Wage Investigations Unit at the NYC Department of Design and Construction (DDC), where she managed investigations into payroll, public works, and building services contracts violations, including allegations of underpayment and fraud. She also worked as an Administrative Law Judge at both the NYC Department of Consumer Affairs (DCA) and the Office of Administrative Trials and Hearings (OATH), where she adjudicated cases concerning breach of home improvement and construction contracts, licensing, permits, deceptive trade practices and fitness proceedings, and later served as the Associate Director of the Adjudication Division at DCA. Ms. DeFontes started her legal career as an Assistant District Attorney in the Domestic Violence Bureau at the Office of the Bronx District Attorney. She received her J.D. from the City University School of Law (CUNY).

Diane Leonard

Diane Leonard is the Executive Assistant. Ms. Leonard began work in the in the Mayor's Office in 1977 under Mayor Abraham Beame. She was assigned to work as an Office Aide for the Midtown Enforcement Project, a federally funded program which focused on law enforcement initiatives in the Times Square area of Manhattan. That project became the Office of Midtown Enforcement and ultimately the Office of Special Enforcement. Throughout her service, Diane has remained a steadfast, professional and trusted member of the administrative staff. Diane earned an Associate of Applied Science Degree from New York City Community College (CUNY).