(JTA) — Belgian prosecutors indicted a Frenchman accused of aiding a gunman kill four people at the Jewish Museum of Belgium.

The defendant, Nacer Bendrer, was extradited from France earlier this week and formally charged with complicity in a terrorist attack on Thursday, the French news agency AFP reported.

Bendrer, 26, was arrested in December near Marseille in France. In May, police in that city arrested Mehdi Nemmouche, a French national who is currently standing trial for the murders last May. Belgian and French authorities believe Nemmouche, who denies killing anyone, is a Muslim fanatic who carried out the attack after returning from Syria, where he had fought with jihadists.

Bendrer has denied any connection with Nemmouche at the time of his arrest.

Police said they found a Kalashnikov style assault rifle, two automatic pistols, a hunting rifle, and a magazine and ammunition when Bendrer was arrested.

Video surveillance footage of the attack on the Jewish Museum shows a man armed with a Kalashnikov.

Federal prosecutors confirmed late last month that the authorities were looking for a possible accomplice to Nemmouche.

On January 15, Belgian police carried out a series of raids to foil what they said was an imminent Islamist plot to kill police officers. Two suspected militants were killed.