Mounir el Motassadeq, 28, should receive the longest sentence possible under Germany's legal system for providing logistical support to the al Qaeda cell that included the man suspected of being the lead Sept. 11 hijacker, said Prosecutor Walter Hemberger.
"The defendant decided to sacrifice himself to an ideology that despises humanity," Hemberger told the court.
El Motassadeq, the first suspect in the world to go on trial for the Sept. 11 plot, is charged with more than 3,000 counts of being an accessory to murder and membership in a terror organization.
During more than four hours of closing arguments, prosecutors described the Moroccan student as an adherent to an extremist ideology and a member in good standing of the closed, secretive al Qaeda cell in Hamburg. El Motassadeq appeared to listen intently, at times stroking his beard but showing no obvious emotion.
His lawyers said he is innocent.
"Everything that the defendant did was neutral and has been interpreted as evil," said Hartmut Jacobi, one of el Motassadeq's lawyers.
His fate will be decided by a five-member panel of judges could impose a sentence up to the maximum or they could acquit el Motassadeq and release him. The defense is scheduled to make its closing arguments on Feb. 12. It was not immediately known when a ruling would be issued.
El Motassadeq has said he was acquainted with at least six Hamburg-based members of al Qaeda, including suicide hijackers Mohamed Atta, Ziad Jarrah and Marwan al-Shehhi. But he denies knowing anything of their plot.
Hemberger, however, said el Motassadeq was himself a member of the terror organization, and accused the defendant of lying repeatedly to authorities. "He was closely integrated into Atta's group," the prosecutor said.
El Motassadeq, who came under suspicion shortly after the attacks, at first claimed he never traveled to Afghanistan, but testified later that he attended an al Qaeda training camp there.
While other members of the cell disappeared after the attacks, el Motassadeq remained in Hamburg, maintaining his innocence in interviews with authorities and the media.
His trial neared an end Tuesday after the court refused defense requests to call new witnesses and the chancellor's office, citing the need to protect intelligence, refused a second request for files from alleged al Qaeda recruiter, Mohammed Haydar Zammar, who is in Syrian custody.
The moves drew protests from the defendant. "Why are people shutting away the truth and saying at the same time that I'm the one who doesn't want to tell the truth? This is unfair."