Paris, France (BBN)-One of the attackers who killed 129 people in Paris has been identified by French investigators.
French citizen Omar Ismail Mostefai was named by local media and a French parliamentarian, reports BBC.
The 29-year-old had a criminal record and was known to have been radicalised.
Investigators identified him after his severed fingertip was found at the Bataclan concert hall, where three attackers blew themselves up, AFP news agency reports.
Friday's attacks, claimed by Islamic State (IS) militants, hit a concert hall, a major stadium, restaurants and bars in the French capital.
Prosecutors say seven assailants- armed with Kalashnikovs and suicide belts- were organised into three teams, and there are fears that some may have fled the scene.
Prime Minister Manuel Valls has said France will continue with air strikes against IS in Syria, and described the group as a very well-organised enemy.
HISTORY OF PETTY CRIME
Police are trying to find out whether Mostefai travelled to Syria in 2014, judicial sources told AFP.
His father and brother have been taken into police custody.
"It's crazy, insane. I was in Paris myself last night, I saw what a mess it was," Mostefai's older brother told AFP before being detained after voluntarily attending a police station on Saturday.
Mostefai came from the town of Courcouronnes, 25km (15 miles) south of Paris.
He lived in the nearby town of Chartres until 2012, according to the local MP and deputy mayor Jean-Pierre Gorges.
He had a history of petty crime but was never jailed.
The security services deemed him to have been radicalised in 2010 but he was never implicated in a counter-terrorism investigation.
Mostefai's brother said he had not had contact with him for several years following family disputes, but said he was surprised to hear he had been radicalised.
He was one of six children in the family and had travelled to Algeria with his family and young daughter, the brother said.
BELGIAN LINK?
The investigation is also focusing on a possible link to Belgium after police there arrested three men near the French border.
A black Volkswagen Polo with Belgian registration found at the Bataclan had been rented by a Frenchman living in Belgium, the Paris chief prosecutor said.
The French national was identified while driving another vehicle in a spot check by police on Saturday morning as he crossed into Belgium with two passengers.
The BBC's Hugh Schofield in Paris says investigators are working on the theory that these three may be another team of attackers who managed to flee the scene.
Speaking in Paris, chief prosecutor Francois Molins told reporters: "We can say at this stage of the investigation there were probably three co-ordinated teams of terrorists behind this barbaric act.
"We have to find out where they came from... and how they were financed."
Molins said the police were also investigating a black Seat used by gunmen at two of the attacks, which remains untraced.
The Greek authorities say two people under investigation by the French police had registered in Greece as Syrian refugees.
A Syrian passport was found near the body of one the attackers at the Stade de France.
An Egyptian passport has also been linked to the attacks.
French President Francois Hollande has imposed a state of emergency after the worst peacetime attack in France since World War Two.
It is also the deadliest in Europe since the 2004 Madrid bombings.
ATTACK SITES:
La Belle Equipe, 92 rue de Charonne, 11th district - 19 dead in gun attacks
Le Carillon bar and Le Petit Cambodge restaurant at rue Alibert, 10th district - 15 dead in gun attacks
La Casa Nostra restaurant, 92 rue de la Fontaine au Roi, 11th district - five dead in gun attacks
Stade de France, St Denis, just north of Paris - explosions heard outside venue, three attackers and bystander dead
Bataclan concert venue, 50 Boulevard Voltaire, 11th district - 89 dead when stormed by gunmen
Islamic State released a statement on Saturday saying "eight brothers wearing explosive belts and carrying assault rifles" had carried out the attacks on "carefully chosen" targets, and were a response to France's involvement in the air strikes on IS militants in Syria and Iraq.
Shortly before, President Hollande said France had been "attacked in a cowardly shameful and violent way".
"So France will be merciless in its response to the Daesh [Islamic State] militants," he said, vowing to "use all means within the law... on every battleground here and abroad together with our allies".
BBN/SK/AD