Atta's Odyssey

Before we get to his dislikes and disorders, his vexations as a child and his entanglements as an adult, let's poke inside Mohamed Atta's brain the night before he helped slaughter 7,000 people. "You have to remind yourself to listen and obey that night, for you will face situations that will require your obedience 100 percent," reads a letter found in Atta's luggage and in the belongings of two other hijackers. Atta would be happy to know that his evil was steadfast.

Though investigators are still excavating the hidden trails that led to Sept. 11, many point to Atta as the linchpin of the 19-man hijacking gang. From Hamburg, Germany, to South Florida to Las Vegas, Atta crossed paths with at least seven other hijackers. While some of these terrorists were barely out of their teens, Atta turned 33 days before the attacks. He seems to have been the center of gravity, the dour and meticulous ringleader. This is the story of how his malevolence was unleashed.

In Egypt, where Atta grew up, his family and friends describe a shy, unassuming young man who struggled to make his mark. They say he must have undergone a stark personality change to become the terrorist who supervised Sept. 11. Born in Kafr El Sheikh, a city on the Nile delta, Mohamed was the son of a lawyer and a homemaker. As a kid, his father says, he liked to play chess and disliked violent games. He was a scrawny youth--only 5 ft. 7 in. and until recently quite thin. (His dad called him "Bolbol," Arabic slang for a little singing bird.) Atta seemed overshadowed by his two sisters, who rose to become a zoology professor and a medical doctor. Atta graduated from Cairo University with a degree in architectural engineering and was an average student, according to his peers.

Atta made a few friends in school, but he was such a loner that when a classmate, Iman Ismail, drew a caricature of their class, she depicted Mohamed standing next to a sign posted on Egyptian military fences: COMING NEAR OR TAKING PHOTOS PROHIBITED. When it came to politics and religion, topics no Egyptian can avoid, he offered mainstream opinions. His friends don't remember ever seeing him pray, and they recall his harsh words for Islamic terrorists--"brainless, irresponsible people."

Which is why several of his Egyptian classmates could not accept his guilt in interviews with TIME. "I could never imagine him on a plane threatening people, killing people," says Ahmed Khalifa, 33, Atta's best friend at Cairo University. "He would be scared to death...He was not a leader. He had his opinion, but he was modest in everything. His emotions were steady, and he was not easily influenced or swayed. Mohamed was well liked because he never offended or bothered anyone." Says Ismail: "He was good to the roots."

But he had what could be interpreted as some ominous undercurrents. Atta could get exercised by the world's shortcomings, big and small. He spoke out impulsively against injustice. He was so sensitive that he could become emotional if an insect was killed. "He was a little bit pure," says Khaled Kattan, another classmate. "If he thought that I said or did something wrong, then he would say that in front of anybody."