Mounir el Motassadeq, 28, showed no emotion but occasionally shook his head or checked his watch as he listened to the verdict finding him guilty of more than 3,000 counts of accessory to murder.
He's the one, prosecutors alleged, who was left behind – the messenger boy, the payroll clerk, the all-around handyman to the 9-11 hijackers.
It was el Motassadeq who used a bank account to pay expenses for the Hamburg apartment where the hijackers met and plotted. It was el Motassadeq who witnessed chief hijacker Muhammed Atta's will and joined the others at al Qaeda training camps in Afghanistan.
Judge Albrecht Mentz said el Motassadeq lied when he testified he was unaware of the plot despite being close friends with Atta, Marwan al-Shehhi and other cell members.
The defendant was "a cog that kept the machinery going," Mentz said. He "belonged to this group since its inception. ... He knew and approved the key elements of the planned attacks."
Sept. 11 victims' relatives who participated in the trial as co-plaintiffs — some offering emotional testimony that Mentz said prompted him to impose the maximum sentence — praised the verdict.
Joan Molinaro of New York City said she was "thrilled."
"It's the first small victory we've had since 9/11," said Molinaro, whose firefighter son Carl was killed at the World Trade Center. "I kind of feel like, 'OK, Carl, we got one,'" she said. "I think my son is smiling."
Another New Yorker, Kathy Ashton — whose son Tommy was killed at the World Trade Center — called the 15-year sentence "a drop in the bucket, especially for a young man, but at least it's something."
After being hammered by the U.S. for not backing war with Iraq, German officials seemed to relish their own victory for U.S. terrorist victims, reports CBS News Correspondent Jim Stewart.
"It is surely a warning to all those who may think about becoming involved in a terorist network," said Interior Minister Otto Schily.
While suspects in the plot detained in the United States face possible death sentences if convicted, el Motassadeq's sentence translates into a minimum of 10 years with 15 months off for time served. Even defendants in Germany sentenced to life in prison generally serve at most 15 years.
Don't look for this fellow to be on trial in the U.S. any time soon, says CBSNews.com Legal Consultant Andrew Cohen. Even if Germany were willing to extradite him now – and that's a long shot, given that country's opposition to the death penalty here – he would demand access to al Qaeda operatives and that's something prosecutors so far have been reluctant to do.
It's also not clear that he could be charged or convicted of anything more than he's been convicted of overseas, so Cohen doesn't expect U.S. officials to push for el Motassadeq's extradition.
El Motassadeq, a slight, bearded man who admitted receiving al Qaeda training in Afghanistan, denied the charges during his 3½-month trial. The defense, which had argued the evidence was circumstantial, said it would appeal.
In addition to 3,066 counts of accessory to murder, el Motassadeq was convicted of five counts of being an accessory to attempted murder and an accessory to bodily injury — charges introduced so five wounded survivors of the attacks, including a Navy officer at the Pentagon, could join the trial as co-plaintiffs.
Mentz said it was hard to give a man with two small children the maximum sentence, but that he had to consider the enormity of the crime and el Motassadeq's lack of contrition even after American co-plaintiffs told the court of their suffering.
Witnesses illustrated el Motassadeq's enthusiasm for the plot, the judge said.
"Al-Shehhi said, 'There will be thousands of dead', and the defendant said, 'We will dance on their graves,'" Mentz said, citing witness testimony.
Schily said the penalty was severe, a judgment shared by a lawyer representing many of the more than 20 American family members and survivors who joined the prosecution in efforts to secure the maximum sentence.
"They wanted justice and they got justice," said lawyer Ulrich von Jeinsen. "They accept that we have another system and since he got the maximum sentence they will be satisfied."
Stephen Push, whose wife was killed in the plane that crashed into the Pentagon, also praised the Hamburg judges, but added: "I'm just disappointed that the German legal system doesn't allow for penalties that are appropriate for crimes of this nature."
El Motassadeq was raised in a Moroccan middle-class family, came to Germany as a student in 1993 and married a Russian woman. By 1995, he was studying electrical engineering in Hamburg, where he is believed to have first met Atta no later than the following year.
He acknowledged being friends with Atta, al-Shehhi and other alleged members of the Hamburg cell including suicide pilot Ziad Jarrah; and Ramzi Binalshibh, Said Bahaji and Zakariya Essabar, all suspected of helping organize the cell.
Witnesses said el Motassadeq was as radical as the rest of the group, often talking of jihad — holy war — and his hatred of Israel and the United States.
Prosecutors allege he used his power of attorney over al-Shehhi's bank account, to pay rent, tuition and utility bills, allowing the plotters to keep up the appearance of being normal students in Germany. They also noted that he signed Atta's will.
El Motassadeq explained both as things he simply did for friends.
He denied for nearly a year after his arrest ever having been to Afghanistan. But on the first day of trial, he admitted training in one of Osama bin Laden's camps there in 2000, saying he thought it was a Muslim's duty to learn self-defense.