The trial of Abdelkader Merah, brother of Mohamed Merah, is the first arising out of a wave of violence by mostly homegrown radical Islamists that has claimed the lives of more than 240 people in France in the past five years.
Abdelkader is accused of knowingly facilitating his brother's attacks on a Jewish school in the south western city of Toulouse, in which a rabbi, two of the rabbi's children, aged three and five, and an eight-year-old girl were killed.
The March 2012 assault, which Merah carried out in the name of Al-Qaeda, was the deadliest on Jews in France in three decades.
In a nine-day killing spree, the 23-year-old also shot dead three soldiers in the garrison town of Montauban before being killed by police after a 32-hour siege at his home.
Investigators believe Abdelkader -- who neighbours nicknamed "Ben Ben" over his admiration for Al-Qaeda leader Osama bin Laden -- had considerable influence over his brother.
The 35-year-old, who lived in the high-rise Toulouse suburb of Les Izards, was known to police for links to ultraconservative Salafist groups.
He admitted to being present when his brother stole a scooter that was used in the attacks, but denied any knowledge of his intentions.
The trial lifted the lid on a dysfunctional family, in which three of five children born to Algerian immigrant parents came under the spell of radical Islamists.
Both Abdelkader and Mohamed spent time in prison for acts of delinquency -- an experience that radicalised the younger Merah and left him thirsting for revenge against France.
In 2011, he travelled to the lawless tribal regions of Pakistan near the border with Afghanistan to join the Qaeda-affiliated Jund al-Khalifa.
Returning to France, he was questioned by intelligence services but insisted his trip had been solely for tourism.
The families of Merah's victims have been pinning their hopes for justice on the trial of Abdelkader, who defended his brother in 2012, declaring: "Every Muslim would like to give his life to kill his enemy."
Prosecutors have presented him as the real brains behind the attacks and called for him to be given life in prison, without possibility of parole for 22 years.
Merah's lawyers have urged the jury not to make him a scapegoat for his brother's crimes to satisfy the public thirst for a conviction.
"Don't make him a symbol of terrorism, make him a symbol of our justice system," lawyer Antoine Vey urged during Tuesday's summing up.
A friend and fellow defendant of Abdelkader's, Fettah Malki, is also charged with complicity in the attacks for supplying Mohamed Merah with a machine gun and a bullet-proof vest.
Prosecutors have called for him to be given a 20-year sentence.