Seven people went on trial in Paris on Monday accused of traveling to Syria to train as militant fighters, among them the brother of one of the militants who killed 130 people in the French capital last November.
The seven, aged from 24 to 27, face up to 10 years in jail if found guilty of taking part in an Islamist recruitment network and receiving training in Syria from Islamic State.
The accused, friends from eastern France, were part of a larger number who in December 2013 traveled to Syria, where two of them died.
All but one returned to France in early 2014. The one who stayed behind was Foued Mohamed-Aggad, who took part in the three-man team that killed 90 people at the Bataclan concert hall during the multiple attacks in Paris.
Two of the three killed themselves by exploding their suicide vests and another was shot dead by police.
Foued's brother, Karim Mohamed-Aggad, is among the seven accused.
The defendants told investigators they had believed they were going to Syria on a humanitarian mission or to fight Syrian President Bashar al-Assad's forces but not to become Islamist militants.
"I went there with one goal only: to fight the regime of Bashar al-Assad," Karim Mohamed-Aggad told the court.
Mohamed-Aggad urged the court not to confuse him with his brother. "You choose your friends, not your family," he said. "My brother did what he did, he alone bears responsibility."
The group's defense team says the seven were duped and when they realized they had fallen into the hands of a militant network they looked for a way out.
"They were told they could be useful," said Martin Pradel, lawyer for one of the defendants, told Reuters ahead of the hearing. "Their mistake was to believe the propaganda."
His colleague Xavier Nogueras said: "This is the trial of seven youths who came back after three months. That will allow us to highlight the difference between those who decided to come back and the one who stayed."