In the spring, shortly after her son's murder, Latifa Ibn Ziaten took a taxi to Les Izards, a hard-up immigrant neighborhood here, hoping to understand. She approached a group of young men to ask, "Do you know Mohammed Merah?"
Mr. Merah, a 23-year-old French-Algerian who claimed to have ties to Al Qaeda, had killed Ms. Ibn Ziaten's son Imad, a sergeant in the French Army, with a gunshot to the head. Before dying in a police raid in March, Mr. Merah admitted that killing and those of two other soldiers, a rabbi and three Jewish children. He spent much of his short life in Les Izards.
"Mohammed Merah, you know, he's a hero, he's a martyr of Islam," the men said, Ms. Ibn Ziaten recalled. "You haven't seen what it's like to live here?" they continued, gesturing toward their neighborhood of beige housing projects and gravelly concrete. "At least he showed the French what power is."