Abdelhakim Dekhar was arrested yesterday after a major manhunt following a shooting at the left-wing newspaper Liberation that left an assistant photographer seriously hurt and another at the headquarters of the Societe Generale bank.
His DNA matched samples from the scenes of the attacks, officials said.
"All the evidence today points to his involvement in the events that he has been charged with," Interior Minister Manuel Valls said.
He served four years in jail for his role in the killings, and his former lawyers have described him as "enigmatic" and "strange".
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Dekhar was arrested last evening in a vehicle in an underground parking lot in the northwestern Paris suburb of Bois-Colombes, after apparently trying to commit suicide.
Valls said that "everything appears to point to a suicide attempt", and sources told AFP Dekhar was semi-conscious when he was found.
Valls said investigators would need more information to be able to "understand his motivation", adding that "one or two letters" had been found.
Investigators said the letters were "confused" and sought to "explain this act."
In a press conference, Paris prosecutor Francois Molins said the letters spoke of a "fascist plot," touched on "how suburbs are run" and accused the media of participating in the "manipulation of the masses".
Molins said Dekhar was in detention for attempted murder and kidnapping.
One of them was a man who had housed the suspect, said a source connected with the investigation.
The witness quoted the suspect as saying "I've made a stupid mistake.