Amedy Coulibaly, the gunman who killed four hostages at a Paris kosher supermarket, rented a small suburban house the week before the attack and filled it with an arsenal of up-to-date weaponry, police have said.
A search of the house has enabled police to identity a potential fourth attacker as investigators follow the money and supply systems for the three known killers, all of whom died in police raids.
Police say as many as six members of the same radical Islamic terror cell may be at large.
“We have put our finger on some extremely dangerous people, men and women,” French police union spokesman Christophe Crepin said. “We are really in a war.”
Of special interest is the small attached house on a quiet street in the town of Gentilly south of Paris that Coulibaly rented about two weeks ago.
Police refused to say what was discovered inside, but newspaper Le Parisien said detectives from the Paris Criminal Brigade and a special police anti-terrorism unit seized a scooter there that allowed them to identity “a fourth man” who acted as Coulibaly’s accomplice.
The newspaper did not identify the man by name, but said he may have shot and seriously wounded a jogger in nearby Fontenay-aux-Roses on January 7, the same day two friends of Coulibaly, brothers Cherif and Said Kouachi, killed 12 people at the offices of Charlie Hebdo magazine.
“The fourth man”, who has a lengthy criminal record, may have been involved in that attack, Le Parisien said, adding that he may have already escaped to Syria.
Neighbours in Gentilly said they had noticed nothing out of the ordinary. One said muscular, 5ft 5ins Coulibaly had been a regular at the local gym.
Officials said the attackers accumulated a veritable arsenal that included three late-model Kalashnikov assault rifles, a rocket-propelled grenade launcher, a machine pistol, smoke grenades and bombs, fragmentation grenades, handguns and industrial explosives.
In addition to the weapons, investigators are painstakingly following the money trail. Former drug-dealing associates of Coulibaly said he was selling marijuana and hashish in the Paris suburbs as recently as a month ago.
Multiple French news accounts have said the Kouachi brothers sold fake sporting goods made in China.
Mr Crepin said police believe the killers did not have the resources to bankroll the terrorist operation on their own.
Not only was there the cost of weapons, ammunition and equipment to cover, he said, but also money needed to rent suspected hideouts like the one in Gentilly and to pay their living expenses.
“We’re dealing with a well-organised mafia-like structure,” he said.
But Peter Neumann, director of the International Centre for the Study of Radicalisation, King’s College London, said that in keeping with the guidelines laid down in an influential handbook for jihadis published in 2004, he believes the Paris attacks were self-financed.
“They could use credit-card fraud, even stealing from people,” he said. “Their attitude is the whole of society (in Europe) is rotten infidels.”
A regional French newspaper has unearthed one additional revenue source: a loan for €6,000 that Coulibaly obtained on December 4 from a consumer-lending company based in northern France.
In a video made public after all three terrorists had been shot dead by police, Coulibaly said he had given the brothers €7,000 so they could buy gear.
But two US intelligence officials said they doubted that Islamic State-affiliated Coulibaly co-ordinated in advance with the Kouachi brothers, who said they were acting on behalf of al Qaida in Yemen.
Al Qaida in Yemen claimed responsibility for the brothers’ attack yesterday, but it had been unclear which brother had made that connection.
Yesterday the US officials said Cherif Kouachi was believed to have gone to train in Yemen in 2011, but used his brother Said’s ID.
Despite their ties to rival Islamic terror groups, the personal bonds between the three homegrown French terrorists were apparently stronger than the divergent strains of radical ideology.
Coulibaly and Cherif Kouachi reportedly met when both were in prison in 2005 and a French judicial document obtained by The Associated Press news agency said both subsequently became “students” of Algerian-born Islamist Djamel Beghal, who was convicted of plotting to blow up the US embassy in Paris.
Other radical organisations may be linked to the cell. French authorities want to locate a man seen with Coulibaly’s widow, Hayat Boumeddiene, on CCTV footage after landing at Istanbul’s airport on January 2.
Her travelling companion has been identified as French-born Mehdi Belhoucine, 23, whose older brother was convicted and sentenced to a year in prison in 2014 for his part in a network to recruit fighters for Afghanistan and Pakistan.
Turkish officials said Boumeddiene crossed over into Syria. Belhoucine’s whereabouts have not been made clear.
Another piece that could aid French authorities in solving the puzzle may be in Bulgaria. Acting on a European arrest warrant, authorities there jailed Joachim Fritz-Joly, a reported friend of the younger Kouachi, as he tried to cross into Turkey.
At a court hearing on Tuesday, Joachin denied being part of a terrorist ring, saying: “A man can have friends and they can do whatever they want, but I am simply going on vacation and have nothing to do with it.”
He was ordered to be held in custody until another hearing can determine whether he should be extradited by Bulgaria to France.