PARIS (Reuters) - The French investigation into last week's Paris shootings is exploring the possible role of Djamel Beghal, an Islamist suspected of first bringing the gunmen together and putting them on the path from impressionable youths to cold-blooded killers.
While the 49-year-old Algerian has denied through his lawyer any involvement in the attacks, judicial and prison sources have described how two of the three gunmen nonetheless fell under his spell during a joint 2005 stretch in jail and then pursued contacts with him after leaving prison.
"Beghal is the crux of the case," said a source close to the inquiry, which on Tuesday ordered searches in the cell in the high-security prison in the western city of Rennes where he is now serving time for an unrelated conviction.
"He is a sorcerer, a seducer," Louis Caprioli, deputy head of France's DST anti-terrorist intelligence unit from 1998 to 2004, told Reuters on Wednesday of a man whose own journey to radicalization passed through London's Finsbury Park mosque during spells living in Britain in the late-1990s.
Barely a week after attacks on the satirical weekly Charlie Hebdo and a Jewish deli, French authorities are scrutinizing security, intelligence and penal structures to see how the three days of violence could possibly have been averted, Prime Minister Manuel Valls and other officials have said.
The fact that all three of the killers and their links with Beghal were known to authorities for years has not gone unnoticed. The government has acknowledged "shortfalls" in intelligence and is putting prison procedures under review.
At this stage in the inquiry, major questions remain open on how the two Kouachi brothers and deli killer Amedy Coulibaly nurtured their plans, and whether a claim of responsibility by al Qaeda in Yemen issued on Wednesday is plausible.
But thousands of pages of French court documents from their past brushes with the law, on which Reuters has been briefed, shed light on the 7-month period in 2005 when Beghal, Coulibaly and Cherif Kouachi - the younger of the two brothers - crossed paths in prison and again five years later in rural France.
Born in 1965 in the small town of Bordj Bou Arreridj east of Algiers into a family of 10 children, Beghal secured his school-leaving certificate and moved to France in 1986, gaining French nationality seven years later.
In the late 1990s he lived briefly in the English Midlands city of Leicester and London, where he attended the Finsbury Park mosque, run at the time by radical cleric Abu Hamza.
As he moved more deeply into radical circles, Beghal spent 2000 at a training camp in Afghanistan and was arrested a year later in Abu Dhabi. He alleges he was tortured there before being sent back to France.
Convicted for his role in a group behind a failed 1999-2001 plot to blow up the U.S. embassy in Paris, Beghal was sent to the sprawling Fleury jail outside the French capital where Cherif Kouachi and Coulibaly would also end up serving time.
Already, Beghal was a beguiling figure, described in one psychological profiling as by turns amiable and menacing. Judicial sources said he built up a "little group of believers" fascinated by his notoriety and religious knowledge.
"He has a gift for being able to convince on the rightness of his cause," said Caprioli, the former deputy head of France's DST anti-terrorist intelligence unit. "Anyone who came into contact with him could not have helped but become more radicalized."
It was in Fleury jail, that Cherif Kouachi, arrested for his role in a jihadist recruitment cell, and Coulibaly, jailed for his part in a bank raid, crossed paths from January to August 2005.
Coulibaly subsequently confirmed to investigating judges that he struck up a friendship with Beghal which others noted coincided with a stark change in his character.
Notably, judicial sources say it was at this time that the "quiet, cheerful and polite" 22-year-old with a love of motorcycles started to express radical Islamist ideas.
The widespread phenomenon of radical Islam in French jails spread by so-called "recruiters", and the inability to stem its rise, was the subject of a Reuters investigation in May 2013.
Yet here was a difference: as a known threat, Beghal had been placed in isolation - a fact confirmed by Khalil Merroun, a former Muslim chaplain at Fleury who by telephone recalled paying him five or six visits, always in solitary confinement.
France's justice ministry also states Beghal was always kept away from other inmates. But prison guards and other penal system sources acknowledge that overcrowding, overwhelmed guards, and inmates' guile can thwart that system.
"Someone in isolation is not necessarily miles away from the rest in detention. If you yell from the windows, you're heard," said Jimmy Delliste, head of the Nanterre jail outside Paris, an authority on the French prison system.
Other methods include hand-scrawled messages thrown from windows or signs flashed; instructions between prisoners passed by visitors or corruptible guards on the take; and Fleury's infamous "yo-yos" - tightly rolled sheets used as rope between windows to pass objects from cell to cell.
One prison administration source doubted that a prisoner in isolation could thoroughly radicalize another detainee from scratch but noted: "Is it 100 percent watertight? No."
The Justice Ministry recognizes it is not always possible to guarantee complete isolation. But it argues it would not have been possible for Beghal to have radicalized other prisoners.
Whatever links grew between the three in Fleury, they were strong enough to lay the ground for further meetings five years later in the incongruously bucolic setting of France's Cantal region, where Beghal had been assigned to house arrest.
Here he ended up in "Les Messageries" motel in the little town of Murat, nestled in a mountainous part of France better know for its long-horned cows and hard cheeses.
Paid for by the interior ministry, the room hand-picked by the prefect, mayor and gendarmerie was ideal for surveillance.
"They ordered up a room, we had to put him up," the owner, who did not want to give her name, told Reuters. Beghal never gave her any problems in his year at the motel apart from the difficulty in finding halal meat for him.
In early 2010, both Coulibaly and Cherif Kouachi, now out of jail themselves, paid a number of visits to Beghal in Cantal that were monitored by intelligence forces, judicial sources said, citing the court documents.
It was during such weekend visits that Coulibaly's companion Hayat Boumeddiene - whom Turkish authorities say crossed into Syria on Jan. 8 - was photographed in a full-faced veil posing with a crossbow, the same documents show.
Coulibaly said in later testimony the visits were harmless, spent "reminiscing about prison, talking about the mountains."
Yet phone calls intercepted at the same time between Beghal and Smain Ali Belkacem, an Algerian Islamist imprisoned for his role in one of the 1995 attacks on the Paris transport system that killed eight, pointed to a plot to spring Belkacem from jail.
The intercepts show the two men spoke in code: "bird" for helicopter, "suit" for car, "books" for weapons and "marriage" for attack." It was during one such conversation that Beghal mentioned another plan he was building "brick by brick."
"Because a blow with a pickax is worth more than 10 blows with a garden hoe," he added, using an Algerian adage in a conversation investigators noted was "more than troubling" yet not substantial enough to conclude he was planning any attack.
Weeks later, police pounced, arresting Beghal, Coulibaly and Kouachi for their part in the conspiracy to break Belkacem out of jail. Beghal and Coulibaly received further jail sentences, while Kouachi was later dropped from the case.
There is no indication that the "pickax" plan was in any way the germ of last week's attacks. Beghal subsequently told investigators it was simply a project to give legal support to others, who like him had been stripped of French nationality.
Beghal's wife Sylvie, who lives in Britain, has issued a statement to CAGE, an advocacy group working against alleged injustices carried out in the name of state anti-terrorism policies, protesting his innocence.
"This man being held up as the representative of (late al Qaeda leader Osama) bin Laden in France is nothing more than a common delinquent," his lawyer Beranger Tourne told Beur FM, a favorite radio station of France's North African community.
Yet the al Qaeda propaganda and other jihadist videos seized in the police raid on Beghal's motel room was enough to convince investigators of his "unquestionable adhesion to armed Jihad".
At his trial, he was convicted to 10 years in prison which Beghal, now stripped of his French nationality, is serving in the ultra-modern Rennes-Vezin le Coquet prison.
As the sieges of the Kouachi brothers and Coulibaly played out Friday, Beghal was moved to a top-security isolation ward. His lawyer said Tuesday's cell searches were "unfruitful"; the investigation into last week's killings goes on.
Writing by Alexandria Sage and Mark John; editing by Janet McBride