According to the FBI:
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.
Wikipedia describes Agent O’Neill:
John Patrick O’Neill (February 6, 1952 – September 11, 2001) was an American counter-terrorism expert, who worked as a special agent and eventually a Special Agent in Charge in the Federal Bureau of Investigation until late 2001. In 1995, O’Neill began to intensely study the roots of the 1993 World Trade Center bombing after he assisted in the capture of Ramzi Yousef, who was the leader of that plot.
He subsequently learned of al-Qaeda and Osama bin Laden, and investigated the 1996 Khobar Towers bombing in Saudi Arabia and the 2000 USS Cole bombing in Yemen. Partly due to personal friction he had within the FBI and federal government, O’Neill was pushed out of the Bureau in 2001. He became the head of security at the World Trade Center, where he died at age 49 in the September 11, 2001 attacks. In 2002, O’Neill was the subject of a Frontline documentary The Man Who Knew, and cast as the protagonist in the television miniseries The Path to 9/11 and the 2003 book, The Man Who Warned America.
Below, you will find what has been release, thus far, of Agent O’Neill’s FBI file.
There is still an open request that I have for additional records. If any exist, they will posted, when they become available.
The following documents were obtained on CD-ROM, and were in the following order. I preserved their order due to their size, and organization:
1315356-0 – 67E-HQ-679605 – Section 1 Serial 1 COVER SHEETMediaPage.PDF [417 Pages, 18MB]
1315356-0 – 67E-HQ-679605 – Section 2 Serial 1 COVER SHEETMediaPage.PDF [293 Pages, 16MB]
1315356-0 – 67E-HQ-679605 – Section 3 Serial 1 COVER SHEETMediaPage.PDF [310 Pages, 15MB]
1315356-0 – 67E-HQ-679605-S (CG) – Section 1 Serial 1 COVER SHEETMediaPage.PDF [174 Pages, 7.7MB]
1315356-0 – 67E-HQ-679605M (CG) – Section 1 Serial 1 COVER SHEETMediaPage.PDF [182 Pages, 22MB]
1315356-0 – HQ 263-2169 – Section 1 Serial 1 COVER SHEETMediaPage.PDF [72 Pages, 2.1MB]
According to the original FOIA response, additional records may have existed. So, I requested those, and received a letter that they believed more documents existed, however, they could not find them. Additionally, they believed that these possible additional records, were destroyed.
John P. O’Neill Additional Documents Destroyed [4 Pages, 1.2MB]