Raised in a tough Toulouse suburb, Mohamed Merah´s life was a bitter progression from juvenile delinquent to violent jihadist

His criminal career began with a volley of rocks – a handful of stones hurled at a passing bus by a bored delinquent.

It ended in a hail of 300 bullets, fired by France´s most elite police after a 32-hour siege worthy of a Hollywood action movie.

In the space of a few years, Mohamed Merah rose from petty criminal to lethal jihadist – a man who fired at point blank range into the heads of school children, murdering seven people in a nine-day rampage.

The 23-year-old´s violent life story finally came to an end on Thursday morning, when police in Toulouse shot him in the head after an intense six-minute gunfight.

How did a small-time thief become a terrifying "lone wolf" terrorist, suspected of travelling throughout the Middle East to receive jihadist training? Why did he kill in cold blood three soldiers, a Jewish teacher and three young schoolchildren? Who was the real Mohamed Merah?

His childhood friends in the tough northern Toulouse suburb of Izards all want answers.

"I just cannot believe he did all that," said 22-year-old Nico – a gangly, tracksuited youth with the hood of his sweatshirt pulled tightly around his pale face. "He was one of us; he wasn´t some religious fanatic. He never even went to the mosque." Aimen, a youth worker in his thirties whose sister is married to Merah´s oldest brother, added: "Everyone is in shock. It doesn´t seem real yet."

Aimen was initially a suspect himself in the murders, and exactly 24 hours before the raid on Merah´s flat, 40 armed police shot down Aimen´s door in a dawn raid and arrested him. Owning the same kind of motorbike as the assassin, he initially fitted the profile. "I have the bullet holes in my living room walls to show for it," he said grimly. "It was a huge shock to me. But then this whole story is shocking. People here thought he was just one of them"

And indeed, his childhood was one shared by millions of young men across France. Born in Toulouse to a family of Algerian origin, Mohamed grew up in Izards with his two sisters - Aicha, who is not religious, and the more devout Souad - plus two brothers, Abdelkader, 29, and his eldest sibling, Abdelghani.

Yesterday, Merah´s mother, Zoulikha, 54, said she was "wracked with guilt" at having been unable to prevent his killing spree. "She is asking herself whether she could have stopped him," said her lawyer, Jean-Yves Gougnaud, speaking after she was released from police custody late on Friday.

But a rather different note was struck by Merah´s brother Abdelkader, who was with him when he stole the scooter used in the drive-by shootings, and who is now being questioned in Paris. He said he was unaware Mohamed was planning the attacks, "but was very proud of him". Yesterday, French media also reported that Abdelkader´s mobile phone had been found near the scene of Jewish school where his brother killed three children and a teacher, and that the two men had dined together the night before. His brother´s message of defiance came as it was further revealed that the family had connections to an imprisoned al-Qaeda suspect. Merah´s mother had married the father of Sabri Essid, 22, who was arrested in Syria in 2006 at an al-Qaeda safe house for militants en route to Iraq. Merah visited Essid in a French prison, and sent him money. He had also, in January, visited a radical Syrian-born preacher known as "The White Emir", who drew young fundamentalists to his home 30 miles outside Toulouse.

The seeds of Merah´s own radicalism, though, seem to have sown amid the social housing tower blocks of Izards, where children loiter on street corners and weave through the warren of passageways on bicycles. His parents divorced when he was around five years old, and his father Mohammed began spending most of his time in Algeria, leaving the young Merah straying into trouble.

"He was not a good student," said his lawyer, Christian Etelin. "He was expelled often and moved from one school to another. He dropped out at a young age."

Merah found work at a car mechanic´s workshop in the town, labouring there for two years. He loved cars, and his friends showed The Sunday Telegraph the scruffy gravel yard behind the football pitch where they would race around in borrowed cars and on motorbikes. At 17 he was arrested for the first time, for being part of a group of youths who stoned a bus. He graduated to vandalism and theft, being detained 18 times and becoming very familiar to the troop of stony-faced police who marched around the estate.

"The same kids get detained time after time," said one woman in her 50s, sitting outside a café in Izards. As she spoke, a group of youths burst around the corner of the tower block, pursued by navy- clad police in bulky stab vests, carrying pistols and stun guns. As one youth was spreadeagled against a wall and searched, his friends jeered at the police.

"It´s like this every day," the woman said. "All they do is chase you, search you, and insult you," added Nico, Merah´s childhood friend. "They hate us and we hate them."

In December 2007, Merah was imprisoned for 18 months for the violent theft of an elderly lady´s handbag. It was here, according to Francois Molins, chief prosecutor of Paris, that he fell under the spell of radical Islam. Some 80 per cent of French prison inmates are believed to be Muslim.

"The prison was just full of kids like him – young troubled men from the suburbs," said Mr Etelin, the lawyer, who had represented him since 2005. "The judge threw the book at him, with no opportunity for early release. That´s when he became convinced of the injustice of the system. He began to hate society."

On Christmas Day 2008 he tried to commit suicide, and was held in a psychiatric unit for 10 days. Alain Penin, a psychiatrist who analysed him in mid January 2009, said he had "normal" intellect but "a disposition towards antisocial behaviour".

French investigators believe that Merah turned to Salafism – which urges adherents to recreate the piety of Islam´s original followers – in prison.

"Salafism is very black and white in that you are told: ´Do this, and you will go to paradise.´ For someone who is messed up and looking for order it is a very attractive philosophy," said Dr Peter Neumann, director of the International Centre for the Study of Radicalisation.

He said that Richard Reid, the British shoe bomber, converted to salafism in Bolton Young Offenders´ institute, but that the French – unlike their British counterparts – had not made countering radicalisation in prisons enough of a priority.

A family friend, who gathered with other neighbours at Merah´s sister Souad´s small council flat in central Toulouse last week, told The Sunday Telegraph that Merah "rediscovered" Islam in prison, having largely ignored his family faith as a young man.

"I tried to talk to him about his beliefs," said the friend, a bearded man in Islamic dress. "But he just said ´It´s between me and my God, and I don´t have to explain myself to anyone.´"

Upon his release from prison, Merah knocked on the door of the Toulouse recruiting centre of the Foreign Legion, long known for being willing to take recruits with a chequered past. However, after spending just one night there, he left without any explanation. "That, even more than prison, made him feel that he would definitely never have a place in French society. That´s when something happened to him," said the lawyer, Mr Etelin.

Nonetheless, his friends in Izards had no idea he harboured secret jihadist plans. "He never mentioned anything to do with Afghanistan," said Nico. "Sometimes he´d go abroad, but he said he was visiting family in Algeria. When he came out of prison he went through a phase of dressing in a funny way, wearing bandanas, and he even had his hair styled into a pink quiff. He was all about fashion, not radicalism."

Others in the district, however, did see the darker side of his double life.

"Two years ago he grabbed a kid off the street in Izards, and made him watch bloody videos of beheadings in Afghanistan," a woman named Malika told a local newspaper. "The mother found out and complained, but the police did nothing. Merah then went for revenge and turned up at the family´s house in full military clothes, waving a sword and chanting ´Al Qaeda! Al Qaeda!´"

The police, she claimed, ignored it. "They aren´t bothered about Arabs arguing with other Arabs."

By the end of 2010 he was once again on the radar – but this time, in Afghanistan.

"He entered via the Iranian border, almost certainly passing through Turkey," said one security officer. "According to our preliminary investigations, he was alone."

American forces stopped him at a road block in the Taliban stronghold of Kandahar and returned him to France, putting him on their No Fly list and banning his travel to the USA. A year later, though, he travelled to Pakistan, spending two months in the tribal heartland of Waziristan – a hotbed of al-Qaeda and Taliban. Here he is thought to have received training, although probably not in an organised camp.

"It is just impossible to fly there, turn up at someone´s door and say ´Hello! I´ve come to join a training camp!´" said Jean-Charles Brisard, an al-Qaeda expert, who believes that Merah simply craved al- Qaeda´s notoriety. "He had a camera strapped to his chest, during the murders, and wanted to be famous. Al-Qaeda associations would give him that."

In November 2011, Merah was questioned by police over his Pakistan trip, but convinced them of his innocence with a slideshow of his "holiday snaps".

During the siege negotiations, he reportedly told police that he was acting in revenge for the death of children in Palestine, out of hatred for the French army´s international missions, and to punish France for banning the Islamic veil.

Whatever his motivation, however, questions are now being asked over how he was overlooked by the French security services. Certainly the size of the arsenal he stockpiled – at least eight guns, including a Kalashnikov assault rifle and an Uzi machine pistol – raises questions about how someone known to the authorities could purchase such weapons.

Yesterday police video footage also emerged of his bullet-riddled flat, showing how he had turned it into a virtual fortress, complete with barricades which he hid behind as he exchanged fire with police marksmen.

And amid the feverish speculation and the increasingly tense presidential campaign – there is less than a month to go until the first round – the government of President Nicolas Sarkozy has defended its surveillance systems and praised the forces for resolving the situation.

Claude Gueant, the interior minister, who was a frequent fixture at the scene of the siege, said there had been no grounds to arrest Merah before the attacks.

"The DCRI (police investigators) follows lots of people involved in radical Islam. Expressing ideas, espousing salafist beliefs, is not a sufficient reason to arrest someone," he said.

Mr Sarkozy took to the stage on Thursday night in Strasbourg, hours after the death of Merah, to promise new anti-terrorism laws. Thumping his fist on the dais, and against a backdrop that read "For a strong France", he milked the opportunity to appear as a firm, capable leader.

Marine Le Pen, the far-Right Front National challenger, tried to do the same, claiming that the French political elite had ignored her own warnings of about "radicalisation".

Back in Izards, though, tensions are also rising, with some visiting journalists attacked last week and the police attracting even more hostility than normal.

"There is trouble on the horizon," said one resident. "It´s been simmering for a while, but this is a powder keg situation that is going to explode." (© Copyright of Telegraph Media Group Limited 2012. 03/25/12)