 A grand jury was empaneled and began taking testimony.A complete list of witnesses to testify there is not known, in part because Fitzgerald has conducted his investigation with much more discretion than previous presidential investigations.Some individuals have acknowledged giving testimony, including White House Press Secretary Scott McClellan, Deputy Press Secretary Claire Buchan, former press secretary Ari Fleischer, former special advisor to the president Karen Hughes, former White House communications aide Adam Levine, former advisor to the Vice President Mary Matalin, and former Secretary of State Colin Powell.