Tuesday's main witness at the Paris terror trial was the 28-year-old Tunisian, Sofien Ayari. He was arrested in Brussels at the same time as Salah Abdeslam, engaging in a gun battle with police officers. On the basis of DNA evidence, he is accused of having helped in the preparation of the Paris attacks.
This trial, in particular the testimony of the mother of one of the victims, has changed Sofien Ayari.
"I did not plan to speak here," he explained, "but there are things that made me change my mind.
"Some of the victims were angry," he said of earlier evidence from the civil witnesses.
"One woman, who reminded me a lot of my mother, said she would take us in her arms, that she felt sorry for our parents. That woman lost her daughter.
"All she wanted to know was what we had been thinking. What made us do it. I believe I owe her an answer. If I was in her place, I wonder if I would have the same courage. I'm not sure.
"I can't give her back her daughter. This is the only thing I can do."
Later in the day, through their lawyer, a group of victims and families spoke of their "relief" that Ayari had chosen to testify. "They view that as a mark of respect," the lawyer said.
Political motivation, not religious
Earlier on Tuesday, Sofien Ayari denied any radicalisation, but admitted that he had gone to Syria in late 2014 with the intention of joining Islamic State as a fighter.
"I left Tunisia, not mainly for religious reasons, but for political ones."
In 2015, he was badly wounded in combat against Syrian troops near the city of Homs, needing four operations on a facial injury which had left his lower jaw "completely ripped off".
He rejected the violent propaganda of IS, saying "there were terrible mistakes made on both sides. That's not to excuse anything. But it was a war.
"I took some decisions on the spur of the moment. I was 21 years old. I did my thinking on an emotional basis. When they told me I was needed elsewhere, I left," he said, explaining how he was recruited for a mission far from the Syrian war zone.
"And did you know that your mission would be a violent one?"
"The question is not as black-and-white as you make it sound," came the response.
Regrets
'I can admit that I was wrong'
"Each of us is responsible for his own decisions," Ayari told the court, in response to a question about his regrets.
"You think back, you think about what led you take such a choice. Then, when you see that the result was so far from the original intention, the least you can do is admit that you were wrong.
"No one forced me to do anything. You can make a bad decision. That doesn't mean you have no regrets.
"My mother, my father, my children were not among the victims. I cannot imagine the suffering of those who lost someone close to them. If I had believed it was a good thing to do, I think I would have taken part. I condemn that sort of attack, but both sides have to play by the same rules."
Islamic State has always justified the Paris killings as a response to French air force attacks on IS positions in Syria, in which civilians were among the victims.
'What do you know about my feelings?'
Sofien Ayari was generally cooperative, answering questions when he could, occasionally taking refuge in forgetful evasion. Not all his answers were to his own advantage.
He clearly did not like the state prosecutor, Camille Hennetier, telling her that if she went on asking the same questions, she should expect to get the same responses.
Nor did he appreciate the suggestion by another lawyer that he had expressed no feelings for the Bataclan victims. "What do you know about my feelings," he asked his questioner, angrily. "I have nothing to say to you."
The trial continues.
