Mr. O'Neill was a native of Atlantic City, New Jersey. Mr O'Neill holds a Bachelor of Science Degree from American University in Washington, D.C., and a Master of Science Degree in Forensic Science from the George Washington University, Washington, D.C.
Mr. O'Neill was appointed a Special Agent of the FBI in July, 1976. Upon completion of his training assignment at the FBI ACADEMY, Quantico, Virginia. Mr. O'Neill was assigned to the Baltimore Office of the FBI in October, 1976 where his investigative assignments included Foreign Counter intelligence, Organized Crime, and White Collar Crime.
In April, 1987, Mr. O'Neill was reassigned to FBI Headquarters, Washington, D.C., where he served as a Supervisory Special Agent in the White Collar Crime Section. In 1989, Mr. O'Neill was assigned to the FBI's Inspection Division. In 1991, Mr. 0'Neill was appointed the Assistant Special Agent in charge of the Chicago Office of the FBI, with overall responsibility for the Violent Crime, White Collar Crime, Drug and Organized Crime Programs. In August, 1994, Mr. O'Neill was designated Inspector-in-Charge of a multi-agency task force investigating possible domestic terrorism violence in the U.S.
In January, 1995, Mr. O'Neill was appointed Chief of the FBI's Counterterrorism Section at FBIHQ, with responsibility for the direction and support of all of the FBI's international and domestic counterterrorism investigations and planning. In this position, he oversaw several FBI investigations, at the national level, such as the capture and extradition of World Trade Center bombing suspect Ramsey Yousef in Pakistan; the investigation of the bombings of U.S. facilities in Saudi Arabia. In August, 1998, he supervised the investigations into the bombings of U.S. Embassies in Kenya and Tanzania.
Mr. O'Neill served as the FBI representative on the Interagency Counterterrorism Committee of the National Security Council. He is active member of the Terrorism Committee of the International Association of Chiefs of Police.
Mr. O'Neill assumed the position of Special Agent in Charge of the National Security Division in the FBI's New York Office on January 1, 1997.
Mr. O'Neill retired from the FBI on August 22, 2001 and joined Silverstein Properties becoming the Director of Security for The World Trade Center. On September 11, 2001, Mr. O'Neill was killed as a result of the terrorist attack on The Trade Center Complex.