Thomas J. Pickard
It was announced by the Associated Press and CNN on the April 9, 2004, evening news that Pickard is to testify before the National Commission on Terrorist Attacks Upon the United States on Tuesday, April 13, 2004, just prior to Attorney General John Ashcroft. According to the news report, Pickard is to testify that, when he approached Ashcroft with information regarding terrorist threats, Ashcroft appeared to be interested in other things.
This is corroborated by the Washington Post's Walter Pincus and Dan Eggen, who write on April 10, 2004, "Former FBI acting director Thomas J. Pickard, who will also testify, has told the commission in private that Ashcroft had little interest in terrorism in the summer of 2001, numerous sources have said." 
Matt Bivens, in his April 12, 2004, Daily Outrage for The Nation, writes: "Apparently all that long summer of 2001, a frustrated Pickard was writing internal memos critical of Ashcroft's lack of interest in counterterrorism. The AG himself may have stopped flying commercial flights in July 2001 out of terrorism concerns, but that seems to have been the limit of his commitment. That, plus Ashcroft's decision on September 10, 2001, to cut the FBI's counter-terrorism budget by $58 million." 
According to the Associated Press's Karen Gullo, "Pickard's [retirement] announcement was not unexpected but [came] at a critical time for the FBI, [when it was]embroiled in two of the biggest investigations in its history. Pickard [directed] both probes, although other senior officials [were] involved in managing them." 
Then 50, Pickard was "the second high-ranking FBI official to announce plans to leave in the aftermath of the Sept. 11 attacks and since FBI Director Robert S. Mueller III took charge of the bureau in July." 
Gullo says that "Pickard was named deputy director in 1999 by former FBI Director Louis Freeh, who retired in June after a series of controversies and mishaps at the bureau."
Gullo writes that "Pickard started his career as an agent in the FBI's New York office in 1975 and went on to work on a number of high-profile cases. ... Pickard went undercover and offered congressmen bribes as part of the 1979 Abscam probe and supervised the FBI's role in trials in the first World Trade Center attack and the arrest of Ramzi Youssef, charged with plotting to blow up U.S. airliners. 
"He also helped oversee the probe into the explosion of TWA Flight 800, the espionage investigation of former FBI agent Earl Edwin Pitts and the capture in Pakistan of Mir Aimal Kasi, who was convicted of killing CIA workers at a traffic light outside the agency's headquarters." 
- FBI Press Release, October 31, 2001: Retirement of Deputy Director Thomas J. Pickard.
- Elaine Shannon, "The FBI Loses A Key Player. Thomas Pickard, the 27-year agency veteran who is spearheading the country's top two investigations, is stepping down," Time, October 31, 2001.