Mohamed Merah killed three Jewish children, a rabbi and three paratroopers in and around the southern city of Toulouse in March before dying in a standoff with police. Merah claimed links to al-Qaida and said he had received training at an Islamist paramilitary camp in Pakistan.
One of his brothers, Abdelkader, also faces preliminary charges in the case and is in police custody.
The attacks raised painful questions about whether France was failing to integrate the children of Muslim immigrants, like the Merahs, who are of Algerian origin. Many blamed the poverty of the neighborhoods many immigrants and their children live in for driving them to radical Islam.
But a new book by another of Merah brother, Abdelghani, says his parents, particularly his mother, are responsible for Mohamed's radicalization.
According to excerpts published in Le Figaro and other newspapers, Abdelghani made a silent vow on the day of Mohamed's funeral to tell the world how they were raised on anti-Semitism.
"I will explain how my parents raised you in an atmosphere of racism and hate before the Salafis could douse you in religious extremism," he writes in "My brother, that terrorist," due out Wednesday. Salafis are ultraconservative Muslims.
The Merahs' mother was at one point held for questioning but has since been released. Their father left the family for Algeria when the children were young but has since sued the French state for Mohamed's death.
A documentary featuring interviews with Abdelghani and his sister, Souad, treads similar ground and airs later Sunday on French television.
In an excerpt publish in Belgian media, Abdelghani remembers how his mother drove home a message of anti-Semitism.
"My mother always said, 'We, the Arabs, we were born to hate Jews.' This speech, I heard it all throughout my childhood," Abdelghani says in the documentary, according to the RTL.be website.
Souad, on the other hand, declares how proud she is of her brother, Mohamed.