The suspected ringleader of the Paris attacks, Abdelhamid Abaaoud, was among those killed in a French police raid on Wednesday, prosecutors say.
They confirmed the Islamic State (IS) militant had died in a flat in the Paris suburb of Saint Denis.
His body was found riddled with bullets and shrapnel in the apartment.
Interior Minister Bernard Cazeneuve said he had received intelligence that Abaaoud passed through Greece on his return from Syria.
It is unclear whether the Belgian had concealed himself among the thousands of migrants arriving in Greece before heading for other EU nations.
One of the other dead Paris attackers, who blew himself up at the Stade de France stadium, was traced to Greece by his fingerprints, where he was registered as a migrant.
In another development, nine arrests were made in Belgium after searches in connection with Friday’s attacks, and police carried out new searches in France.
2013: Said to have first visited Syria, joining the Islamic State group before slipping back to his home country, Belgium
20 January 2014: Passes through Germany’s Cologne-Bonn airport, en route to the Turkish city of Istanbul. Returns to Syria, where he becomes one of the faces of IS propaganda
15 January 2015: His mobile phone is reportedly traced to Greece from calls made to an Islamist cell in Verviers, Belgium
16 November 2015: Three days after the Paris attacks, a foreign intelligence service alerts France that he is back in Europe, having passed through Greece; police receive a tip-off that he is on French territory
18 November 2015: Killed in police raid on Paris suburb of Saint Denis