CLOSING THE NET THE INVESTIGATION

THE police officer standing outside the shuttered Hamara youth centre in Lodge Lane in Beeston, south Leeds, clearly didn't know if the shout from a group of locals was meant to be a joke or not. "You'll run out of f***ing tape if you block off any more streets" was the call that barely made the officer's head turn in acknowledgement. Blue and white "police line" tape and officers dressed in luminous yellow over-jackets have blocked off acres of streets in Beeston, Holbeck and Burley in Leeds since the identities of the London suicide bombers were discovered. The accelerating police investigation, Operation Thesis, twisting and turning its way through the city's Muslim-dominated suburbs, is threatening and questioning the very idea of what a community is and what it should have known.

"Hamara'' means ''ours". It is supposed to be a term of belonging and pride. It sounds grand - but the Hamara centre in Lodge Road is anything but.

The street is run-down and serves an economically deprived community. The red-brick terraced house converted into the small drop-in centre has old, rusted, graffitti-covered shutters. Last Thursday, it was the focus of a widening police operation that saw four streets around it blocked off. A fleet of buses was brought in to evacuate families in the vacinity; police told them not to expect to return for days. A bomb disposal unit from the Royal Logistics Corp arrived around 11.30am. An hour later they carried out a controlled explosion and sent a radio-controlled robot into the centre.

Through information taken from hundreds of police interviews, the Lodge Lane building was supposed to be an important indoctrination centre, used by Islamic mentors to radicalise some of the young men of the area into taking a journey that was once thought alien to British society - the one taken by suicide bombers, its terminus being the carnage that hit three London Underground trains and a bus on July 7.

The full importance of the Hamara centre might never be understood. But, so far, police know that three of the bombers from Beeston and Holbeck regularly visited the centre.

One of them was Hasib Hussain. He was 18 and the youngest of the bombers. Hussain was from Colenso Mount in Holbeck, a few miles north of Beeston Hill. He was unemployed, had apparently struggled at South Leeds High School and had found it difficult to live with the disappointment of a limited education. He became, according to some who knew his family, "a difficult teenager". His family, from Pakistan, did what many families in similar circumstances do: tried to help him by sending him "home". Hussain was born in Leeds, but the trip to relatives in Pakistan, according to a family friend, "was supposed to give him the values of his parents. They are good people." According to other friends, Hussain may also have attended a religious college (a madrassa) on his Pakistan visit. Others still say that he only visited relatives. His parents also paid for him to go to Mecca for the Haj pilgrimage.

When he came home, the difficult child had apparently changed. He became serious about his religion, began wearing traditional robes, grew a beard and had apparently put his teen tantrums behind him. Were his parents and friends seeing only what they wanted to see?

None mentioned his conviction last year for shoplifting, which was at odds with his newfound devoutness. But Hussain's parents cared.

His mother Manzina cared enough to call the police just after 10pm on July 7, just over 12 hours after the London bombs had gone off. She told police her son Hasib had told her the previous night that he was going to London to meet friends.

A religious conference had also been mentioned.

He had a mobile phone, but wasn't answering it.

She was worried and gave police a full description of what her son was wearing.

Manzina's call was the catalyst that fast-tracked the entire investigation. Hussain had been wearing a distinctively coloured top. Specialist forensic teams had already begun identifying the dead. The "signature" injuries of a suicide bomber - decapitation, the specific patterns of a destroyed body at the epicentre of an explosion - had been found. The burnt and blood-covered top described by Manzina helped identify her son. He was responsible for the carnage on the bus in Tavistock Square.

Officers looking at CCTV pictures were then told to concentrate on King's Cross station.

Hussain was located. He was surrounded by three other men, also believed to be of Pakistani origin.

All four were carrying large rucksacks. For several minutes at around 8.30am the CCTV footage shows them stopping, huddled and seemingly talking. There is speculation this was the four's final ritual prayer, the prayer of "alshaheed al-hayy" - that of a living martyr. "May Allah be with you, may Allah give you success so that you achieve Paradise."

Twenty minutes later, three bombs went off within 50 seconds of each other, hitting Piccadilly Line and Circle Line trains. Around 81 minutes later, Hussian detonated his bomb on the No 30 bus. Police are still trying to discover what Hussain did during his missing 81 minutes. Was he carrying other bombs that have been passed on to others in London?