HAMBURG, Germany — A Moroccan convicted as an accessory to murder in the September 11, 2001, attacks was sentenced yesterday to the maximum 15 years in prison, minutes after telling the son of a woman killed that day, “My future is ruined.”

A federal appeals court convicted Mounir el Motassadeq, who was a friend of three of the suicide pilots, in November of knowingly helping the hijackers and sent the case to a state court in Hamburg for sentencing.

Just before yesterday’s verdict, the 32-year-old defendant spoke with an American whose mother died on board one of the planes that crashed into the World Trade Center.

Dominic Puopolo Jr., a co-plaintiff in the case, earlier joined prosecutors in calling for the maximum penalty, urging the judges to consider the “human and emotional cost” of the 2001 attacks.

“Anyone who helped in this has earned stiff punishment,” presiding Judge Carsten Beckmann said after announcing yesterday’s verdict.

When the court granted Mr. Motassadeq a final chance to speak, the slightly built, bearded man turned to Mr. 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.”

Mr. Puopolo said he forgave Mr. Motassadeq and reminded him that he would one day be freed.

“You have a chance to rebuild your life and be back with your family. Others don’t,” Mr. Puopolo said. “Your life is not over, but my mom’s is.”

Defense lawyers said they may appeal to a European court.

The federal appeals court had ruled that the Hamburg judges wrongly acquitted Mr. 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 Mr. 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.

A lawyer for Mr. Motassadeq, 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.

Mr. 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 Qaeda camp in Afghanistan and that he was close to the three hijackers, but he insists he knew nothing of their plans.

However, the federal appeals court said evidence showed Mr. Motassadeq knew that the hijackers 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 — facilitated the attacks.