While 19 hijackers were among the nearly 3,000 people who died in the Sept. 11, 2001 attacks, many of the men said to be responsible for the worst terrorist incident in U.S. history were nowhere near Washington or New York that morning. Some of the prime actors have been captured or killed, while others remain at large nine years later.
Mohamed Atta The 33-year-old pilot of the American Airlines plane that crashed into the North Tower of the World Trade Center was a ringleader of the coordinated hijacking of four planes. Born and raised in Egypt, he moved to Germany in the early '90s and became part of the Islamic extremist "Hamburg Cell" later that decade. He met Al Qaeda leader Osama Bin Laden in Afghanistan and was recruited to become part of a plot to receive pilot training and then crash hijacked jets into U.S. targets. He died with 18 other hijackers on Sept. 11.
Mohammed Atef Al Qaeda's alleged military chief met with 9/11 planner Khalid Sheikh Mohammed and Al Qaeda leader Osama Bin Laden in 1999 to help plot the 9/11 attacks. He also met with several of the men who would later hijack the jets, including Mohamed Atta, to explain their mission. By then he was already wanted in the U.S. for his alleged role in the 1998 embassy bombings in Africa. He was killed in a U.S. airstrike in Afghanistan in November 2001.
Zacarias Moussaoui The reputed "20th hijacker" has been sentenced to life in prison without parole for his role in the 9/11 plot. Born in France to Moroccan parents, he was arrested in Minnesota prior to the attacks on an immigration violation. Though Moussaoui had received flight training like the other hijackers and money from Ramzi Binalshibh, he has denied that he was part of the 9/11 plot, saying he was part of another Al Qaeda plan for an attack after 9/11. Now 42, he is in a supermax federal prison in Colorado.
Khalid Sheikh Mohammed The admitted mastermind of 9/11 has said that he is responsible "from A to Z" for the attacks. Currently held at Guantanamo Bay, he has said that he wants to plead guilty and looks forward to becoming a martyr. He was captured in his home country of Pakistan in 2003 and was waterboarded while in U.S. custody. He has professed involvement in dozens of terror plots, has been charged with war crimes and faces the death penalty. Mohammed and four other defendants are set to be tried in a U.S. court once a venue has been picked. New York authorities have objected to plans to try the defendants at a courthouse in lower Manhattan near Ground Zero.
Ramzi Binalshibh The Yemeni-born Binalshibh was part of the Hamburg cell with hijacker Mohammed Atta. He received Al Qaeda training in Afghanistan in 1999 and was allegedly supposed to be one of the 9/11 hijackers, but was refused a U.S. a visa four times, later taking a behind-the-scenes role in the plot. He was captured exactly one year after the 9/11 attack, on Sept. 11, 2002, in Karachi, Pakistan by Pakistani and U.S. intelligence agents. After being held at an undisclosed location by the CIA, he was transferred to Guantanamo Bay in 2006, where he remains pending trial.
Osama Bin Laden The founder and leader of Al Qaeda remains at large, most likely somewhere in the mountainous border regions of Pakistan and Afghanistan. Born in Saudi Arabia to a wealthy family, Bin Laden, now 53, founded Al Qaeda more than 20 years ago after taking part in the successful resistance against the Soviets in Afghanistan. While initially denying responsibility for the 9/11 attacks, Bin Laden took responsibility for them in a 2004 taped statement, saying that he had personally directed the hijackers. Bin Laden has been wanted by the U.S. since the 1998 African embassy bombings, but eluded attempts by U.S. forces to capture or kill him in Afghanistan in late 2001. The U.S. believes that he was present during the battle for the Tora Bora cave complex in December 2001, but escaped. The U.S. government has offered a reward of $50 million for information leading to his capture or death.
Ayman Zawahiri The Egyptian doctor was arrested in 1981 after the assassination of Anwar Sadat and accused of being part of an Islamist plot to overthrow the government. Leaving Egypt, he formed an alliance with Osama Bin Laden in Pakistan, merging his Muslim Brotherhood with Bin Laden's Al Qaeda. He issued a joint fatwa with Bin Laden "Against Jews and Christians" in 1998. Now considered Al Qaeda's second-in-command, he is thought to be hiding out, like Bin Laden, in the border area of Pakistan and Afghanistan. He survived a CIA airstrike on a Pakistani village where he was thought to be hiding in 2006, and continues to issue intermittent audio and videotapes urging jihad. The US State Department said in 2009 that it now considers Zawahiri the operational commander of Al Qaeda, with Bin Laden considered an "ideological figurehead."