French authorities contend the gunman in a killing spree in Toulouse took the path to religious radicalization behind bars _ with neither teacher nor network.
They're now looking for ways to detect what may be a new phenomenon in prisons, the arrival of the enigmatic "lone wolf" Islamist radical, already a challenge to law enforcement authorities in the world at large.
The investigation will show whether gunman Mohamed Merah, who claimed al-Qaida links, acted alone in the three March attacks that killed seven people.
But in the meantime, his case has been seized upon by those who say the model for Islamist radicalization in prisons may be changing, away from networks of extremists and toward more individualized paths to radicalism.
President Nicolas Sarkozy ordered a study on the evolving threat in prisons after last month's killings, and the justice minister called for greater intelligence gathering in prisons and more Muslim prison chaplains.
Tracking such "lone wolf" radicals presents prison authorities with a new challenge: detecting the Muslim inmate who is not just turning to religion but turning the corner to danger. Some worry that even tighter surveillance may carry the risk of a double-edged sword, stigmatizing a Muslim population already deprived of the means to properly practice their faith behind bars.
In countries from Europe to the Middle East and Southeast Asia, prisons have long been known as incubators for Islamist extremism, where self-proclaimed imams or convicted terrorists prey on vulnerable inmates.
The problem is acute in France, the country with the largest Muslim population in western Europe, estimated at some 5 million, and, it is said, the most Muslim prisoners. France doesn't count inmates by ethnicity or religion, but one expert estimates that about half of French inmates are Muslim, far greater than the proportion in the population at large.
Yet there are only 151 Muslim prison chaplains to tend to the needs of prisoners of the Islamic faith, compared to 700 Roman Catholic chaplains. Islamic leaders say the dearth of chaplains and the failure to provide basics like halal food for imprisoned Muslims heightens the risk that inmates will feel rejected by the system and seek their own _ possibly radical _ path.
This parallels the emergence of "lone wolf" terrorists in the world at large. Experts say the lone wolf phenomenon is in a way a testimony to succesful Western intelligence, which has made it more difficult for networks to form _ outside or inside prisons.
"In a way this is a modernization of terrorism. They don't need role models," said Farhad Khosrokhavar, who has written a book on Muslims in prison and another on Muslim prison radicals, and is currently researching the development of extremisms of all kinds in French prisons.
A terrorist cell in France, dismantled in 2005, was famously born behind French prison walls with members recruited by a convicted terror accomplice, Safe Bourada.
"My personal view is those parameters that identify ... radicalized (prisoners) have to be deeply revised because they are based on networks," Khosrokhavar said. He estimates the Muslim prison population at 40-60 percent of the 66,455 people in detention in France.
Justice Minister Michel Mercier recently announced he wants a full-time security official devoted to intelligence gathering in each large prison and closer working ties between the prison administration and intelligence agencies. He also wants an increase in the number of Muslim chaplains in French prisons.
"A new phenomenon has appeared, the self-radicalization of some prisoners," Mercier said. "Mohamed Merah read the Quran alone and it is his own interpretation that led him to radicalization."
Sarkozy has called self-radicalization "the worst thing for democracies," apparently referring to the difficulty in detecting this solitary transformation without trampling on civil liberties.
Sarkozy ordered authorities to find new ways to tackle the emergence of a new breed of radicals behind bars after police said the 23-year-old Merah killed three paratroopers, a rabbi and three Jewish school children. Merah was killed March 22 by an elite police squad after a 32-hour standoff at his Toulouse apartment.
Merah spent about a year and half in prison for theft and made trips to Afghanistan and Pakistan after being freed.
There are currently 200 inmates in French prisons under surveillance for radical Islamist tendencies _ 75 of them already imprisoned for actions linked to Islamist terrorism, according to Justice Ministry spokesman Bruno Badre.
The seemingly small number of prisoners tagged as potentially simmering threats has doubled since 2008 and there is a fear that unbeknownst to authorities some inmates may be radicalizing in isolation after petty crimes, like Merah.
French authorities have not elaborated on Merah's path to radicalism, nor have they offered proof that he didn't have teachers or guides. His brother was known as an ultraconservative Muslim, and was handed preliminary charges in the investigation as a suspected accomplice.
Alain Bauer, a leading French criminologist, believes that self-radicalization of Muslims in a prison is rare, and that religion is part of a larger process of finding identity for disenfranchised minorities, "for kids in the middle ... born in France but not French."
"You are just in-between, a mid-level delinquent. You know you won't become chief of the gang." In this context, Bauer said, "religion is just a cover for a personal way to become somebody."
Prison intelligence "gets you on a list where you're surveyed" but doesn't explain the road to radicalization. He says that police didn't understand quickly enough that a gangster can also be an Islamist terrorist.
French prison officials only started acting to detect the risk of Islamist radicalization in the past decade, several years after deadly bombings around the country in 1995 blamed on a brutal Algerian insurgency movement.
Officials trained to decipher early signs of radicalization have been assigned to large prisons on a full-time basis, and part-time in smaller facilities, according to the Justice Ministry spokesman. Since 2002, the ministry collects noteworthy prison intelligence and information can be shared with intelligence services.
Experts say standard overt signs of radicalization can include growing a beard, a change in behavior with prison personnel, notably going from a good to a deteriorating relationship, or even hanging out in the exercise yard with the same group of prisoners.
A "manual of good practices" enumerating what to look for and how to cope with extremism was distributed to prison officials in 2008, produced in a joint effort by experts from France, Germany and Austria. Its contents have never been made public.
While prison officials may track suspected budding radicals or transfer problem cases to another facility, the Muslim chaplain at Fleury-Merogis, France's largest prison, has another approach _ to listen to inmates.
"My role is, above all, to listen ... but if I see there is a lack, a deficiency, then I try to set things straight," said Abdelhak Eddouk.
"When an inmate sees me, he doesn't say 'I'm radicalizing.'" But Eddouk says some inmates have tested him "to see if I know my religion well or not."
He stresses that only a tiny minority of prisoners move toward radicalism and makes a distinction between those with an extremist ideology and those in search of meaning to their lives.
For Eddouk, the cure is connection _ via family ties, prison administrators and chaplins like himself.
"Most prisoners are looking for something to hang onto. They just try to keep standing," he said.