A mound of earth is seen near the grave site of Mohamed Merah, a Frenchman of Algerian origin who was shot dead following a more than 30-hour siege last week, at the cemetery in Cornebarrieu, near Toulouse.

In the neighbourhood where Mohamed Merah grew up, and was last seen joking with friends days after he had killed three French soldiers in a pair of shootings, the message to outsiders is clear: he was one of our own, no matter what he did.

The self-styled Islamist militant tore a wound in France's fragile sense of community when he gunned down the soldiers, sons of North African immigrant families like his own, and then a rabbi and three Jewish children - all in the name of al-Qaeda.

For days, Toulouse lived in fear of the “scooter killer”.

France reeled at the worst such attacks since a bombing campaign involving another young son of Algerian parents from another rough provincial suburb, Khaled Kelkal from Lyon, killed eight people in 1995. President Nicolas Sarkozy put his re-election campaign on hold to call for unity. Tens of thousands of people marched silently in memory of the victims.

But in Les Izards, the 1960s housing project where Merah, 23, felt most at home, the reaction to his rampage has been one of anxious defiance of outsiders trying to peer into what seems like a closed world, cut off from elegant downtown Toulouse by its poverty, by crime and, locals say, by racial discrimination.

“I'm going to tell you one thing: he was a kid from this neighbourhood and we support his family no matter what people say on TV,” said one middle-aged mother of Algerian origin who said she had known Merah when he was a child in Les Izards.

Typical of others in the area of low-rise blocks and tidy squares a 15-minute metro ride north of the city centre, she did not want to be named when speaking up for the man who was, briefly, public enemy No 1: “He was one of ours,” she said. “And we will never be sure of what really happened.”

Dozens of conversations with neighbours reveal a portrait of Merah as a “fragile”, “emotional” young man who spoke constantly of his absent father and had withdrawn into a state of anxiety in his final weeks. They left question marks over his own claims to belong to an identifiable international movement, despite recent travels to the Middle East, Pakistan and Afghanistan.

They also show a powerful sense of alienation from the rest of French society in Les Izards, a community of 5 000, mostly families who arrived from France's North African former colonies a generation or two ago. Merah spent much of his youth living there with his mother, two brothers and two sisters.

Officially labelled a “sensitive urban zone” due to high rates of poverty, joblessness and criminality, Les Izards offers a window into the urban enclaves where French academics say exclusion is deepening and more grandchildren of North African immigrants are turning to Islam as a form of social protest.

The fear is, there may be more Mohamed Merahs in waiting among Europe's largest Muslim community, of some five million people in France - a worry that may partly explain Friday's roundup of 19 suspected militant Islamists as Sarkozy's government asserts a firm grip on security ahead of a series of presidential and parliamentary elections starting on April 22.

In Les Izards, there is evidence of earlier failures in policy, however, notably of Sarkozy's efforts to assuage the rage and resentment that fuelled an explosion of rioting across France in 2005 - and still simmers below the surface.

By one local account of a confrontation between youths and the authorities in the neighbourhood, after Merah was killed trying to escape a siege of his apartment, one young man was arrested after yelling at the police ranks: “My friend Mohamed is a real man - too bad he wasn't able to finish the job!”

Hatem Ben Ismail, who runs several community centres in the area and describes himself as the “go-to guy on Les Izards”, says he simply hesitates to discuss in public the mood among the youngsters he tries to help: “The situation with the young people,” he concluded, “is just too explosive.”

By the bakery where Les Izards residents said they last saw Merah hanging out, two days before his last attack, on a Jewish primary school on March 19, a group of surly young men in tracksuits and dark glasses glowered at oncoming cars.

When, on a reporting assignment this week, a Reuters photographer approached the youths, all in their late teens and early 20s, she was warned, with a stream of expletives, to leave - or have her car smashed up.

Merah's acts have brought unwanted scrutiny to a neighbourhood known to police as a hub for trade in cocaine and heroin, as global media lay siege and police seek to discover whether Merah had help in planning and carrying out his attacks.

Abdelkader Merah, 29, the gunman's older brother, has been charged with complicity in murder and theft and involvement in terrorism. An austere figure and a more overtly devout Muslim than his sibling, who rarely prayed at the mosque, officials suspect Abdelkader may have exerted a strong influence on Mohamed since their father returned to Algeria in 2006 or 2007.

“He was difficult to approach, much more austere and distant than Merah - the sort who did not look women in the eye,” said Patricia, a mother of Italian and Algerian background who had known Mohamed Merah since he was 14 and said she was close to his brother's wife.

Police also suspect that a third man may also have been involved. But in Les Izards, where a movement is under way to mount a demonstration in support of the imprisoned Abdelkader Merah, many simply find the idea of an organised plot by the Merahs and others absurd. Some mutter of official conspiracy.

Mohamed Merah was a playful teenager, zooming between Les Izards' apartment blocks on his motor scooter, no different from many others. A lover of cars and soccer, he went to nightclubs with friends and left school at 16 to work as a panel-beater. Though his travels heightened his interest in Islam, he prayed only infrequently and rarely went to mosque.

“I don't condone what he did, but I can only talk about the Mohamed I knew, who was a kid like all those over there,” said Patricia, who like many found it simply hard to compute the crimes to which police said Merah confessed before being killed.

“When I last saw him he was with his friends by the tobacco shop,” she said. “He played with my boy and gave him two euros to buy candy at the bakery.”

Few of the young men of the neighbourhood would open up to outsiders. Among those who did, some found conspiracy theories more convincing than that one of their own could be a killer who amassed an arsenal of guns and targeted his victims carefully:

“All of this is a setup to get people to vote for Sarkozy,” said Hamed, a boy in his late teens riding a bicycle through the village-like warren of apartment blocks.

Among people who knew Merah and who do accept the police version of events, including his lawyer, the most common explanation is not a calculated militant operation but a fit of rage brought on by a mix of trauma over “horrible” things seen during his travels and disappointment over his breakup with a girl to whom he was engaged in a religious ceremony in December.

Patricia said that Merah may have been upset about the breakup with his fiancee, a woman from a nearby neighbourhood, which coincided with his serving a month in jail in February for driving without a licence. - Reuters