John S. Dempsey is Professor Emeritus of Criminal Justice at State University of New York (SUNY), Suffolk County Community College. He also teaches criminal justice and public administration courses at SUNY, Empire State College, where he serves as a mentor for ranking members of law enforcement and criminal justice agencies. Mr. Dempsey was a member of the New York City Police Department (NYPD) from 1964 until 1988, serving as a police officer, detective, sergeant, lieutenant and captain. He focused on both patrol and investigations. Mr. Dempsey received seven citations for meritorious and excellent police duty.

After retiring from the NYPD, he served as Professor of Criminal Justice at Suffolk County Community College on Eastern Long Island, where he received the college's prestigious "Who Made a Difference Award" for his teaching and work with students. Mr. Dempsey lectures throughout the country on policing and criminal justice issues and is a member of the Academy of Criminal Justice Sciences (ACJS), the International Association of Chiefs of Police (IACP), ASIS International, the Northeastern Association of Criminal Justice Sciences (NEACJS), and the Criminal Justice Educators Association of New York State (CJEANYS).

He has received the Outstanding Contributor Award from the ACJS Community College Section and the Fellows Award from the NEAJS. Mr. Dempsey has written several books on policing and security. He received his Associate of Arts Degree and his Bachelor of Arts Degree in Behavioral Science from the City University of New York, John Jay College of Criminal Justice, his Masters Degree in Criminal Justice from Long Island University and his Master's Degree in Public Administration from Harvard University, the John F. Kennedy School of Government.