French police have identified one of the assailants in the brazen Paris attacks that killed 129 people as a 29-year-old Frenchman, Omar Ismail Mostefai.
Mostefai blew himself up at the Bataclan concert hall, the scene of the bloodiest attack where 89 people were killed.
His father and 34-year-old brother have been taken into custody by police and a source close to the probe said investigators are now searching the homes of other friends and relatives of the killer.
Mostefai, whose identity was confirmed using a severed fingertip, was known as being close to radical Islam, but had never been linked to terrorism.
Police said the attackers appeared to be “seasoned, at first sight, and well trained” and were investigating whether they had ever been to fight in Syria, where IS has proclaimed a caliphate along with territory in neighbouring Iraq.
The Islamic State has claimed the carnage carried at some of the French capital’s most popular night-spots, including a sold-out concert hall, at restaurants and bars and outside France’s national stadium.
Investigators in France, Belgium, Greece and Germany are now trying to find out who these men were, how they carried out such a vast coordinated attack, and why.
From petty criminal to cold-blooded terrorist
Mostefai was known to police as nothing more than a petty criminal before he became the first assailant to be identified from Friday’s Paris attacks.
Born on November 21 1985, in the poor Paris suburb of Courcouronnes, Mostefai’s criminal record shows eight convictions for petty crimes between 2004 and 2010, but no jail time.
Paris prosecutor Francois Molins said Mostefai had been singled out as a high-priority target for radicalisation in 2010 but, before Friday, he had “never been implicated in an investigation or a terrorist association”.
Investigators are now probing whether he took a trip to Syria last year, according to police sources.
“It’s a crazy thing, it’s madness,” his brother told AFP, his voice trembling, before he has taken into custody.
“Yesterday I was in Paris and I saw how this shit went down.”
The brother, one of four boys in the family along with two sisters, turned himself in to police after learning Mostefai was involved in the attacks.
While he had cut ties with Mostefai several years ago, and knew he had been involved in petty crimes, his brother said he had never imagined his brother could be radicalised.
The last he knew, Mostefai had gone to Algeria with his family and his “little girl,” he said, adding: “It’s been a time since I have had any news.”
“I called my mother, she didn’t seem to know anything,” he said on Saturday.
A source close to the enquiry said Mostefai regularly attended the mosque in Luce, close to Chartres, to the southwest of Paris.