After Mueller did a stint as U.S. attorney in San Francisco, President George W. Bush nominated him to direct the FBI. He was sworn in on Sept. 4, 2001, one week before the planes hit the twin towers. For the next 12 years, in both Republican and Democratic administrations, Mueller led the FBI through one of the most difficult periods in its history. The bureau shifted from a domestic law enforcement agency largely focused on criminal threats to a global intelligence organization reoriented to fight terrorism.
