Khalid Shaikh Mohammed turned Usama bin Laden's wish to kill Americans into a reality like no one else in Al Qaeda, U.S. counterterrorism officials say. His capture could lead to a windfall of intelligence about terror attacks still in the works.
Mohammed, one of the most hunted men in the world and the suspected mastermind of the Sept. 11 attacks, was captured early Saturday in Pakistan by Pakistani authorities and officers from the Central Intelligence Agency, according to U.S. and Pakistani officials.
The officials declined to say whether Mohammed had been taken into U.S. custody, where he was captured or where he was being held.
Since Sept. 11, Mohammed has at least twice attempted to smuggle operatives into the United States but has been thwarted, U.S. officials said, speaking on the condition of anonymity. Officials believe he knows the locations of many of the remaining Al Qaeda leaders, perhaps even where bin Laden himself is hiding.
Intelligence on Khalid Shaikh Mohammed's activities was a key factor in the Bush administration's decision to go to orange alert through most of February, U.S. counterterrorism officials said, without providing details. The alert signaled a high risk of terrorist attacks; officials on Thursday lowered the alert level a notch to yellow.
Mohammed was also active in Al Qaeda's attempts to acquire chemical and biological weapons, officials said.
"This is major. This is a dramatic capture of someone who is directly responsible for the Sept. 11 disaster," said Vince Cannistraro, a former CIA counterterrorism chief. "He should be aware of impending operations both in the United States and in other places."
American officials say Mohammed, who was born in Kuwait and holds Pakistani citizenship, worked under bin Laden's guidance to plan and coordinate key aspects of the Sept. 11 operation.
Mohammed has been connected financially to the Al Qaeda operative who funded many of the hijackers' movements and training. His former aide, Ramzi Binalshibh, was a part of the Hamburg, Germany-based terror cell that included chief hijacker Mohammed Atta.
Binalshibh was captured in Karachi, Pakistan, in September.
Mohammed also visited Germany several times in the late 1990s, where officials suspect he contacted members of the Hamburg cell to coordinate the Sept. 11 attacks.
Investigators believe Mohammed spent some time in the United States, attending Chowan College in northeastern North Carolina in the early 1980s before transferring to another American university, where he obtained an engineering degree.
Since the attacks on the World Trade Center and Pentagon, Mohammed has emerged as Al Qaeda's top operations official, counterterrorism officials have said. Only bin Laden and perhaps his chief deputy, Ayman al-Zawahri, ranked higher on CIA target lists.
With Mohammed's capture, Al Qaeda's stable of operational planners grows ever smaller. Other key figures still at large include Saif al-Adil, bin Laden's security and intelligence chief; Shaikh Saiid al-Masri, his financial chief; and operations chiefs Tawfiq Attash Khallad and Abu Musab Zarqawi.
Mohammed has been linked to the April 11, 2002, suicide truck bombing of a synagogue in Tunisia. The bombing, Al Qaeda's first successful strike outside of South Asia since the Sept. 11 attacks, killed 19 people.
The suspected bomber, Nizar Naouar, spoke by phone with Mohammed about three hours before the attack, German officials said. Bin Laden's son Saad, seen as a rising leader in Al Qaeda, is also suspected of ties to the plot.
Mohammed is also on the FBI's most-wanted terrorists list. Last year, a senior American counterterrorism official called him "the most significant operational player out there right now."
He has had a long association with Al Qaeda, officials say.
Mohammed worked with his nephew Ramzi Yousef, now in prison for plotting the 1993 World Trade Center bombing, and two others in the Philippines on a number of operations.
One plan called for blowing up a dozen trans-Pacific airliners in flight. A second involved crashing an airplane into CIA headquarters outside of Washington.
The four plotters were linked to Al Qaeda through a financial operative named Khalifa, who is bin Laden's brother-in-law, officials have said. Khalifa is believed to remain at large.
The plots were stopped in 1995 when Mohammed's associates were arrested, and in 1996 the U.S. government indicted Mohammed for his role. It has offered a reward of up to $25 million for information leading to his capture — the same reward offered for bin Laden.
In January 1996, the U.S. government tried to have Mohammed detained in Qatar and turned over to U.S. authorities, but was unsuccessful, U.S. officials have said. By the middle of the year, the Qatari government reported it had lost track of him, sparking concerns that someone in the government had tipped him off.
Mohammed has not been charged in the Sept. 11 attacks.
He was believed to be in Afghanistan or Pakistan when the attacks took place. Last year, Mohammed and Binalshibh gave an interview to the al-Jazeera television network in which they discussed the Sept. 11 attacks.
He has been known by many other names: Ashraf Refaat Nabith Henin, Khalid Adbul Wadood, Salem Ali, Fahd Bin Adballah Bin Khalid, Abdulrahman A.A. Alghamdi, and Mukhtar, according to various law enforcement and intelligence agencies.
Abu Zubaydah — another senior operative now in U.S. custody — told his interrogators that Mohammed was the organizer of the Sept. 11 attacks.
U.S. counterterrorism officials believe Mohammed went to Afghanistan to join the mujahedeen fighters opposing the Soviet occupation in the late 1980s.
Mohammed is in his late 30s. Interpol describes him as 5-foot-5, weighing 160 pounds, sometimes wearing beard and glasses.