'Khaka' and 'Sid', the committed jihadists who turned to murder

The precise role in the London bombings of Shahzad Tanweer seemed a mystery in the weeks after 7 July. But it has since become clear that he and Mohammad Sidique Khan were by far the most driven Jihadists among the four men who killed 52 people by detonating bombs.

For years, Tanweer's interest in Islam had been as cursory as that of 'Sid' (as Khan was known to friends.) But reverts or converts to the Muslim faith (Khan, Tanweer and bomber Germaine Lindsay) present a greater risk of distorting its teachings than those, like bus bomber Hasib Hussain, who grew up with it.

Tanweer might have been known locally as 'Khaka' ('baby') but he proved himself quite capable of involving himself in territorial battles on lines of race. When the windows of his family's chip shop were smashed following fights between white and Asian youths he resolved to get his own back. The feud resulted in the death of a white boy. Tanweer had no involvement in the murder but did receive a caution for a public order offence arising out of the gang battles.

Khan, whom he first encountered in the 1980s, seems to have worked away at Tanweer's disgruntlement. Both men were members of a group of Asians in Beeston known as The Mullah Crew, whose meeting points included the local Islamic bookshop raided by police after the bombings and a gym beneath Beeston's Hardy Street mosque.

They encouraged disenchanted Muslim boys who had drifted into heroin and alcohol abuse to join them and strengthened those converts physically, often through outdoor activities.

Khan and Tanweer also introduced young men to a distorted sense of what Islam means. Their radicalism was so blatant that the gym became known as the "al-Qa'ida gym", according to Tanweer's associates. But many were prepared to overlook this because The Mullah Crew were perceived to be cleaning up the neighbourhood.

By 2004, as The Independent reveals today, Khan and Tanweer had both graduated to more serious radicalism. Security sources say that, in the same year, Tanweer spent time "without Khan" at a terrorist training camp in Pakistan run by the Harkat-ul-Mujahedeen group - linked to the murder of US journalist Daniel Pearl. He was trained in handling arms and explosives at the camp in Mansehra, near the Kashmir border Tanweer made his journey for this training with Khan. They arrived together in Karachi on 19 November last year and left for Lahore by train a week later before moving on to Faisalabad where their trail disappeared before they surfaced again in Britain on 8 February. By then, Tanweer had visited Mansehra.

On 28 June this year, Tanweer and Khan left Leeds together again - destined this time for London on their 'dummy run' for the bombings. When it came to the real event, Tanweer booked the Nissan Micra rental car for 7 July that would take him, Khan and Hasib Hussain to Luton railway station in readiness for the devastation they would cause.