Jew-hating French comedian Dieudonne M'bala M'bala has been detained by police for a Facebook comment appearing to back terrorist murderer Amedy Coulibaly, reported the BBC Wednesday.
Coulibaly shot dead a policewoman and four Jewish men in separate attacks in Paris.
The Paris prosecutor has begun an inquiry into whether Dieudonne was being an apologist for terrorism. If found guilty, he could face up to seven years in jail.
M'bala M'bala has several convictions for inciting anti-Semitism.
In September, a separate inquiry was launched into a video in which he mocked the decapitation of American journalist James Foley by Islamic State terrorists. There, too, the charges are that he had been an apologist for terrorism.
Hours after 3.7 million people had taken part in rallies across France on Sunday, Dieudonne wrote on his Facebook: "I'm finally going home. Know that this evening, as far as I'm concerned, Je suis Charlie Coulibaly," he wrote, combining the "Je suis Charlie" slogan adopted in support of the 17 victims of the Paris attacks with the name of the terrorist who murdered four Jews at a supermarket.
He deleted the remark a short time later.
Coulibaly murdered a policewoman near a Jewish school last Thursday, before going on to hold up a kosher supermarket, where he murdered four hostages.
Dieudonne's comment drew an angry response on Monday, with Prime Minister Manuel Valls saying that freedom of speech should not be confused with anti-Semitism, racism and Holocaust denial.
Interior Minister Bernard Cazeneuve said he had asked the authorities to investigate Dieudonne's remarks.
The publication of a new issue of Charlie Hebdo on Wednesday was so sought after that the publishers increased the print run to five million copies.
French daily Le Monde pointed out that freedom of speech was limited by French law, and did not extend to incitement to hatred or racism, anti-Semitism and homophobia.
In 2007, the then editor of Charlie Hebdo, Philippe Val, was cleared of inciting hatred against Muslims for reprinting cartoons of the Prophet Muhammad.
Dieudonne was himself acquitted last year over comments made in a video in which he called for the release of a man who tortured and murdered Ilan Halimi, a Jewish man, in Paris in 2006.
His trademark "quenelle" gesture has been criticized as an inverted Nazi salute.