Shahzad Tanweer (search), the 22-year-old son of a Pakistani-born affluent businessman, turned to Islam, the religion of his birth, a few years ago.
The transformation was gradual, but then his relentless reading of the Koran and daily prayers became almost an obsession, his friends told The Associated Press. He became withdrawn and increasingly angry over the war in Iraq, according to those who knew him best.
The U.S.-led war was what likely drove him to blow himself up on a subway train last week, said his friends.
"He was a Muslim and he had to fight for Islam. This is called jihad," or holy war, said Asif Iqbal, 20, who said he was Tanweer's childhood friend.
Another friend, Adnan Samir, 21, nodded in agreement.
"They're crying over 50 people while 100 people are dying every day in Iraq and Palestine," said Iqbal. "If they are indeed the ones who did it, it's because they believed it was right. They're in Heaven.
"Have you ever been inspired in life?" he asked.
Tanweer and three other bombers detonated their backpacks on a bus and three subway trains in London on July 7, killing at least 53 people, themselves included, and injuring more than 700.
Tanweer turned to religion before the war in Iraq began in 2003. His friends don't know the reason, but said they didn't see anything wrong or unusual about it.
"He always told me to read the Koran and said Islam is the way [of life]," recalls Iqbal.
Everyone interviewed in his neighborhood — those who knew him well like Iqbal and Samir, who were schoolmates, or those who saw him in passing — described Tanweer as pleasant and kind.
"He was a nice lad. I don't know how many times he served me fish and chips," said Peter Douchworth, 58, a Beeston resident for over 30 years. "He went out of his way to help."
Tanweer sometimes worked at his father's fish and chips shop, but an employee there said he hadn't worked there for a while.
The family's white house — which has been cordoned off by police since Monday — stands in stark contrast to the surrounding gritty red-brick Victorian row houses. Two fancy cars are parked in the parking lot at the back.
A devoted athlete, Tanweer studied sports science at Leeds Metropolitan University (search) and planned to get involved in sports professionally. He showed up twice a week for pickup soccer games, said a teammate who gave his name only as Saj.
He had a younger brother and two sisters and always lived in the working-class multiethnic Beeston area of the city of Leeds in northern England.
Media reports said he was arrested once for shoplifting.
His uncle, Bashir Ahmed, said Tanweer traveled to Lahore, Pakistan, this year to study Islamic religion. He said his family believed he was attending "some religious function" on the day of the bombings.
Forensic evidence has linked Tanweer to the blast on the Underground train near Aldgate.
Friends Iqbal and Samir claimed ignorance as to how their friend became involved in Islamic militancy and how he became a prey to terrorist recruiters.
"All Muslims are connected," Iqbal said.
The friends said they had never been approached by anyone trying to indoctrinate them into militant Islam.
Where would Tanweer and his co-activists meet or plan their attacks?
"How do football fans get together and talk about football? It's the same thing," said Iqbal.
Tanweer's friend, Hasib Hussain (search), is another of the bombers identified by police. At 18, the handsome, 6-foot-tall soccer player was the youngest of the bombers. He was also the youngest of four children, two sisters and a brother. Like Tanweer, his family came from Pakistan.
Hussain, suspected of carrying out the suicide attack that claimed 13 lives on a double-decker bus, was known for his sense of humor and style. He sometimes wore blue contact lenses and long hair parted in the middle, according to a friend.
Some people said Hussain became more religious two years ago but never abandoned his boyhood friends for radicals. Mohammed Sidique Khan (search), 30, born in Pakistan and another of the suicide bombers, is known in his neighborhood as an exemplary community worker.
A father of an 8-month-old baby girl, Khan was a popular former teacher of children with learning disabilities.
Documents belonging to Khan were found in the debris of the Edgware Road subway blast.
Former students at the Hillside Primary School (search) said Khan left for Pakistan last December to look after his ailing father. It was not clear when he returned to Britain.
"I liked him. He was nice," said Billy Sandersen, 13. He and other former pupils said they were shocked when they saw his picture in the papers as one of the suspects.
However, they said they still liked him.
"Just a little bit, but not for what he's done — killing innocent people," Sandersen said.
"I still like him," said Sean Woodham, 13, another former pupil, "because he always helped me with my homework."
Maroof Latif, an unemployed Beeston resident, said he knew Khan since he was a child and believes if he took part in the terrorist bombings of the subways it was because of his anger over the war in Iraq and the U.S.-British occupation.