A Moroccan convicted as an accessory to murder in the Sept. 11, 2001, attacks was sentenced Monday to the maximum 15 years in prison. A federal appeals court in November convicted Mounir el Motassadeq, a friend of three of the suicide pilots, of knowingly helping the hijackers and sent the case to a state court in Hamburg for sentencing. "Anyone who helped in this has earned stiff punishment," presiding Judge Carsten Beckmann said after announcing Monday's verdict. Shortly before the verdict, the 32-year-old defendant exchanged charged words with an American co-plaintiff whose mother died on board one of the two planes that crashed into the World Trade Center. Dominic Puopolo Jr. fought back tears and held up pictures of his mother as he joined prosecutors in calling for the maximum penalty, urging the judges to consider the "human and emotional cost" of the 2001 attacks. When the court granted El Motassadeq a final chance to speak, the slightly built, bearded man turned to Puopolo to say, "I understand your suffering. ... The same thing is being done to me, my kids, my parents, my family - my future is ruined." Puopolo said he forgave el Motassadeq, and reminded him that he will one day be freed. "You have a chance to rebuild your life and be back with your family. Others don't," Puopolo said. "Your life is not over, but my mom's is." The federal appeals court had ruled that the Hamburg judges wrongly acquitted el Motassadeq in 2005 of direct involvement in the attacks, even though they sentenced him to seven years in prison for belonging to a terrorist group. The appeals court convicted el Motassadeq as an accessory to the murder of the 246 passengers and crew members aboard the four jetliners used in the attacks, and ordered the state court to set a new sentence. El Motassadeq's attorney Udo Jacob argued in vain for the hearings to be halted pending a decision by the Federal Constitutional Court on an appeal filed last month. It is unclear when that court, Germany's highest, will consider the case. Lawyer Ladislav Anisic said they would seek a retrial and maybe appeal to the European Court of Justice. "We have a clear mandate, and that is to ensure that our client receives the acquittal," he said. El Motassadeq was a close friend of pilots Mohamed Atta, Marwan al-Shehhi and Ziad Jarrah when they lived and studied in Hamburg. He has acknowledged training at an al-Qaida camp in Afghanistan and that he was close to the three hijackers, but insists he knew nothing of their plans. However, the federal appeals court said evidence showed el Motassadeq knew that the men planned to hijack and crash planes. It found that his actions - for example, transferring money and helping the hijackers keep up the appearance of being regular university students by paying tuition and rent fees - had facilitated the attacks. The federal court also said it was irrelevant to el Motassadeq's guilt whether he had known of the plot's timing, dimension or targets.