Traore allegedly recited verses from the Quran as he beat Ms Halimi, before throwing her from a third-floor window.
"I've killed the Shaitan [devil]," the 29-year-old reportedly shouted.
Traore has confessed to the murder, but in a preliminary ruling on Friday, a judge who will decide whether he will stand trial said it was possible he was not responsible for his actions because he had smoked cannabis beforehand, Le Parisien reported.
Several psychiatric evaluations conducted after the killing found Traore was in a state of "acute delirium" provoked by his excessive use of cannabis, the paper said.
Traore claimed to smoke up to 15 joints a day.
While the three psychiatric assessments agreed Traore does not suffer from mental illness, they disagreed on whether he was completely responsible for his actions.
The judge also dismissed the "aggravating circumstance of the antisemitic character" of the murder, Le Figaro reported, citing a source close to the case.
An aggravated element of hate crime had been added to Traore's indictment months after the murder.
Lawyers for the plaintiff announced they would appeal the ruling, French newspaper 20 minutes reported.
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