But the court proceedings were also tense, peppered by clashes between the plaintiffs and the defense team, which repeatedly argued that there was no evidence that Mr. Merah knew about his brother’s plans and that the court should not convict him for his brother’s crimes.

Image Abdelkader Merah, the older brother of the Toulouse gunman Mohammed Merah. Credit... Agence France-Presse — Getty Images

“I say and I say again that I have nothing to do with the assassinations that my brother carried out,” Mr. Merah told the court on Thursday before the verdict. His defense lawyers had asked for his acquittal.

Asked about comments made after the attacks in which he had expressed pride in his brother’s actions, Mr. Merah told the court that he now condemned them and felt “a mix of sadness, shame and regret.”

Mr. Merah was tried over five weeks in a special court for terrorism crimes before a panel of judges rather than a jury. He was arrested and charged in the days after his brother’s shootings, and has been in pretrial detention since.

In court, prosecutors depicted Mr. Merah as a radical Islamist who indoctrinated his younger brother and helped him logistically, notably by helping him steal a Yamaha TMax scooter and buy a motorcycle jacket, which were used by the gunman during the shootings. Mr. Merah said he did not know the items would be used to carry out a terrorist attack.

Speaking to reporters outside the courtroom in central Paris after the verdict, Éric Dupond-Moretti, Mr. Merah’s lawyer, said that the judges had “resisted pressure from public opinion” and called his client a “fake culprit who was fabricated to satisfy their thirst for justice.”

Two of Mr. Merah’s siblings, both at odds with the rest of the Merah family, described a toxic family environment where hatred of Jews, Americans and France was commonplace. Mr. Merah’s mother, upon learning about the shootings, is reported to have said: “My son brought France to its knees.”