Mohamed Merah was killed by a sniper after a gunbattle with police that ended a more than 30-hour siege at his Toulouse apartment.
During the siege he admitted killing three three Jewish schoolchildren, a rabbi and three soldiers in three separate attacks.
The investigation is now moving to his brother Abdelkader, who has been whisked to Paris for further questioning after a police source disclosed he had said he was "proud" of his late sibling's killing spree.
Police found explosives in a car Abdelkader owned, according to the public prosecutor leading the case.
He was already known to security services for allegedly having helped smuggle jihadist militants into Iraq in 2007.
French television station FT2 has aired video showing police walking around the apartment of Mohamed Merah, the 23-year-old gunman responsible for the deaths of seven people in France.
President French Sarkoz, spoke today of his great sadness of the events.
Libby Wiener reports on how the capture and killing of the gunman, has did little to allay French fears.