He was last seen re-entering one of the towers to help more people escape. A former U.S. Marine Corps captain, Hatton started with the FBI in New Orleans, and worked briefly in a small Louisiana office. He was an accomplished crime-scene examiner, a certified bomb technician, and a volunteer firefighter. He transferred to New York in 1991 to become part of a bank robbery task force. Agents described him as generous with his time and insights. Friends and colleagues considered him a humble, friendly, and hardworking person who genuinely cared. He was married with four children. His family accepted the FBI Medal of Valor and Memorial Star in his honor.

Former Special Agent O’Neill retired from the FBI in August 2001 to lead security at the World Trade Center.

Although he escaped from his office in the North Tower after it was struck, he died later helping others evacuate when the tower collapsed. In 25 years as an Agent, O’Neill made a name for himself as a tenacious, hard-charging, and passionate fighter against terrorism. He led the Counterterrorism Section at FBI Headquarters during some of the FBI’s most high-profile investigations, including the Oklahoma City federal building bombing, the attack on U.S. bases in Saudi Arabia, and the pursuit of the first World Trade Center bomber in 1993. He spent his last four years in the New York Office overseeing national security matters. His leadership coordinating the investigations into the bombing of the USS Cole and two U.S. embassies in Africa cemented his reputation in the international counterterrorism and law enforcement communities. He had a son and a daughter. His family accepted the FBI Award for Meritorious Achievement in his honor.