The brother of the man who killed seven people in south-west France in recent weeks has been charged over the murders, judicial sources say.
Abdelkader Merah, 29, is suspected of complicity in murder and theft, and involvement in terrorism. He will be kept in custody, prosecutors said.
Abdelkader Merah denies the accusations but says he was there when his brother stole a scooter used in the attacks.
He also denies being proud of his brother, who was killed on Thursday.
According to his lawyer, Abdelkader Merah "strongly condemns" his brother's actions, saying he is "not at all proud" of them.
"Otherwise, he just hopes he does not become the scapegoat for his brother's acts because this is in some ways what is happening," Anne-Sophie Laguens said.
Mohamed Merah died in a shoot-out with police following a 32-hour siege of his apartment in Toulouse.
During the stand-off, he had admitted shooting dead three soldiers in two separate incidents, and, last Monday, killing three children and a teacher at a Jewish school in the city.
Investigators are trying to establish if Merah, a 23-year-old French citizen of Algerian descent, acted alone.
His older brother - and a woman described variously as his wife or girlfriend - were detained by police on Wednesday, and taken for questioning at domestic intelligence agency (DCRI) headquarters in Paris.
The woman was released without charge earlier on Sunday.
Meanwhile, several thousand people marched in silence through Toulouse and the French capital, Paris, urging unity and tolerance of all religions and cultures following the shootings.
Prosecutors said Abdelkader Merah was presented to a judge in Paris on charges of criminal conspiracy aimed at planning terrorist acts and of complicity in murders and gang robbery.
He was handed preliminary charges of complicity in murder and theft, and involvement in preparing a terrorist attack.
Correspondents say that under French law, preliminary charges are filed when there are strong reasons to suspect a crime was committed, but more time is needed to investigate.
"Police inquiries have produced grave and matching pointers that suggest his participation as accomplice in crimes relating to a terrorist enterprise is plausible," the Paris public prosecutor's office said in a statement earlier.
Police and prosecutors have previously reportedly said Abdelkader is a radical Islamist and that traces of what could be an explosive material were found in his car.
He was questioned several years ago about alleged links to a network sending Toulouse-area youths to Iraq, but no action was brought against him at the time, police sources say.
Mohamed Merah had described himself as an al-Qaeda member, and told police he had bought weapons for 20,000 euros (£16,700; $24,400) using money taken through break-ins and hold-ups.
He recorded the shootings on a video camera strapped to his body.
The brothers' mother, 55-year-old Zoulika Aziri, had also been taken in for questioning, but was released without charge on Friday.
Her lawyer said her world had been "turned upside down" by the events. "At no time could she have imagined that her son was the one who did it," Jean-Yves Gougnaud told reporters in Toulouse.