Nemmouche, 29, who was arrested at a Marseille bus station on Friday, is believed to have gone to Syria to join Islamist groups fighting Bashar al-Assad’s regime in 2013 and was already known to anti-terror police.
He had weapons of the kind used in the attack - a Kalashnikov machine-gun, a pistol and bullets - in his bags, along with a video camera and a cap of the kind the gunmen was wearing, sources told the AFP news agency on Sunday.
Investigators found short video footage, in which he talked about the attack and showed off the weapons, in the camera, Paris prosecutor François Molins said at a press conference on Sunday.
A pennant bearing the name of the jihadi group the Islamis State of Iraw and the Levant was also found, Molins said.
Nemmouche, who comes from the northern French town of Roubaix and told police he was homeless, was travelling on a bus that had come from Amsterdam via Brussels.
He refused to answer questions during the first 24 hours of his detention.
He has been charged with murder, attempted murder and possessing and transporting arms in connection with terrorism.
Under French law he can be kept until Tuesday with the possibility of prolonging his detention until Thursday if investigators claim there is a danger of a further “terrorist” attack.
Four people – a French voluntary worker, a Belgian museum employee and an Israeli couple – were killed in the shooting, which several world leaders declared an anti-Semitic attack.