...snopes debunks it here. It's fiction. Made up.
http://www.snopes.com/rumors/atta.htmThis is a reallly interesting read about Atta.
"On 12 April 1986, Mahmoud Mahmoud Atta (also known as Mahmoud Abad Ahmad), a 33-year-old Jordanian native, ambushed a passenger bus in the Israeli-occupied West Bank. Atta (working with an accomplice) stopped the bus with a firebomb, then opened fire on it with an Uzi, killing the driver and seriously wounding three passengers.
Atta was arrested in Venezuela a year later, but because Venezuela had no extradition treaty with Israel, Venezuelan officials deported him for immigration violations to his country of origin, the United States. (Atta was a naturalized U.S. citizen.) Atta was arrested by FBI agents upon arrival at Kennedy International Airport and held in prison in the U.S. for more than three years before being extradited to Israel for trial in October 1990. His extradition was controversial because the nature of the extradition treaty in effect required that the accused's offense must be of a "non-political nature," and Atta maintained that he had committed political rather than criminal offenses. Nonetheless, the U.S. courts upheld Israel's extradition request on the grounds that Atta had attacked civilian rather than military targets and had therefore committed regular criminal acts, not political acts aimed at the overthrow of a government. In October 1991, an Israeli court found Atta guilty and sentenced him to life imprisonment.
Fast forward ten years. As the U.S. tries to piece together the terrorist plot that resulted in four hijacked airliners and the destruction of both World Trade Center towers, they discover that the mastermind was apparently one Mohamad Atta, who had entered into the U.S. unnoticed and spent well over a year here receiving training at more than one American flight school. Newspapers (both domestic and foreign) begin to criticize U.S. intelligence and law enforcement agencies for allowing a known terrorist to slip into the country so easily :
http://www.snopes.com/rumors/atta.htm