A French national with suspected ties to Islamic radicals in Syria has been caught in Marseille, South of France, in possession of a Kalashnikov, a handgun, and a video in which he claims responsibility for the Brussels Jewish Museum shooting that left 3 people dead, and one man in critical condition, the AFP reports.

The 29-year-old man has been identified as Mehdi Nemmouche. He’s well known by the French authorities, having spent five stints in prison where he is thought to have converted to radical Islam. Nemmouche, who has been described by his aunt as “nice, intelligent, and educated,” went to Syria after his latest prison stay. There, he is believed to have begun fighting alongside jihadists from the extremist group Islamic State of Iraq and the Levant (ISIL).

He had intended to film the attack on a GoPro camera, but it didn’t work. Instead, the suspected murderer “filmed his weapons and said he carried out the attack against the Jews in Brussels,” explained prosecutor Frederic Van Leeuw during a press conference in Brussels on Sunday.

Although Nemmouche’s weapons matched the one used during the shooting rampage, the persecution says it “can’t guarantee that it is his voice on the recording.”

This incident has raised serious concerns over the rise of anti-Semitism in Europe. It also prompted Belgian Prime Minister Elio Di Rupo to call for closer European cooperation on the fight against jihadists. The problem is a sizable one: in France alone, an estimated 780 people went to Syria to join the jihadist fighters.