HAMIS MUSHAYT, Saudi Arabia - At dusk in this nondescript town of modern strip malls and newly built housing blocks, the Seqeley mosque was bathed in a warm, inviting green neon light as worshipers gathered for prayers on a recent evening.
The Seqeley mosque was built as a gift to the town by a branch of the prominent and respected Alshehri tribe known as the Seqeley family, construction firm owners who worked closely with the late building magnate Mohammed bin Laden on the winding highway that cuts through the middle of Hamis Mushayt.
It was in this mosque that four young Saudi men - two brothers from the Seqeley family known as Wael and Walid Alshehri and their friends Ahmed Alnami and Saeed Alghamdi from nearby Abha - are believed by several friends and a local cleric to have taken a solemn oath to go and carry out jihad.
Friends who knew them say they gathered in the mosque in the spring of 2000 to pray and meditate in an informal ceremony that bound them to jihad and, if necessary, to die in the defense of Islam. In the months that lay ahead, they began secretly slipping away from their families.
Eventually, they were swept into Osama bin Laden's Al Qaeda terrorist network, and US investigators say they were among the Saudis who hijacked four jetliners on Sept. 11.
Mohammed Seqeley Alshehri, the father of Wael and Walid, is a tough and uncompromising man who refused to speak to a Globe reporter. But his son Abdel Rahman, 40, one of Wael and Walid's 15 brothers by Mohammed's four different wives, invited the reporter into the family home, which sits across from the mosque. The father and son were returning from evening prayer, and the father was thundering against the Western media in a room inside the home. But Abdel Rahman served tea in a majlis, or reception room, at the front of the sprawling house.
You have to understand my brothers were not Islamic purists began Abdel Rahman, who lived with his brothers in the family compound. They were young, they were bored, and we have no idea what happened to them.
To be very honest, neither one of them was very smart, nor very motivated to do anything, said Abdel Rahman. All of this is impossible for us to believe.
He explained that his father had built the local mosque and was a devout Muslim who refused his sons any link to modernity, for within the strict puritanism of the Wahabi school of Islam these things are strictly forbidden: No satellite TV. No Internet. No music. And definitely no girls until they were old enough for an arranged marriage.
The Alshehris are a military family with three older brothers who hold high rank at the nearby airbase. Their uncle, Major General Faez Alshehri is the logistical director of the kingdom's armed forces. The base - from which the United States staged some of its airstrikes on Iraq during the Gulf War - was attacked in August 2000 by a lone gunman believed to be a follower of bin Laden. The gunman killed a Saudi guard and wounded several British workers there.
Wael and Walid did not serve in the military but were steeped in the family lore of service to the Saudi Air Force, and Wael was a physical education teacher at the sprawling airbase. US investigators have said they believe Wael may have had flight-simulator experience.
The two brothers' personalities were a complex Saudi mosaic. They were devout, but they also smoked Marlboros, cruised Web sites at a local Internet cafe, and liked pop music.
A turning point came late in 1999 when Wael, 25, fell into a deep depression, Abdel Rahman said. His friends say it was not just depression, but perhaps even a suicidal tendency, and he was forced to take a leave of absence from his work as a gym teacher. He went to see a faith healer in Mecca accompanied by Walid, 21, who was just drifting in life, his brother said. It was at this point that the two apparently fell under the sway of a militant Islamic cleric who counseled both to read the Koran, to fast, and to take up jihad.
Sometime in the late spring of 2000, they disappeared and their family did not know where they went, Abdel Rahman said. Friends said they believed the two went to Pakistan and then on to Afghanistan where they were given hand-to-hand combat and light weapons instruction at the Al Farouk training camp. They returned to Saudi Arabia in December 2000 and boasted to friends about their experience.
Through the family mosque and perhaps through militant circles, the two men befriended Ahmed Alnami from the nearby town of Abha.
Alnami, 23, was distinctly middle class. His late father had been an employee of the Ministry of Islamic Affairs and Endowments, and he was the youngest of six siblings.
Alnami played the oud, a traditional Arabic guitar, and had a good singing voice. He would gather with high school friends for bonfires in the wind-swept park atop Souda, the highest point in Saudi Arabia, and make them laugh mimicking the Saudi pop star Mohammed Abdou. He was fond of smoking apple tobacco in a nargilla, a traditional waterpipe. The music, the singing, the smoking all would have been frowned upon as un-Islamic by the men in his family.
Then in the summer and fall of 1999, Alnami began a rapid change, becoming obsessively pious after returning home from a Saudi-government sponsored religious summer camp. One friend said that his family feared that the sharp turn in his behavior was a bipolar disorder. He grew a beard, he shunned his old friends, he stopped playing music. His sweet voice now was used to call the faithful to prayer at the Al Basra mosque in Abha, and occasionally at the mosque in Khamis Mushayt, where he is presumed to have met up with the Alshehri brothers.
When Alnami saw his old friends in Abha, he tried to steer them away from those practices that are evil, as he put it, and toward the right and true path of Islam. He entered King Khalid University's School of Islamic Law, long regarded as a hotbed of Islamic fundamentalism, and it was there, his friends believe, that he delved deeper into militant circles. Apparently he befriended another young Saudi named Saeed Alghamdi, who was also from Abha.
He just drifted away from us and it was like we had lost him, said a high school classmate who works at a publishing company as he stared at old snapshots of Alnami.
When the Alshehri brothers, Alnami and Alghamdi gathered at the Seqeley mosque in the spring of 2000 and made their oath to commit to jihad, friends say the informal ceremony was led by Wael Alshehri, who had assumed a nom de guerre of Abu Mossaeb al-Janubi. Abu Mossaeb was the name of a close friend of the Prophet Mohammed who gave up everything to follow his teaching. Al-Janubi, means of the south.
This meeting was talked about among the groups of men in their 20s who have little to do but gossip on the streets of Khamis Mushayt and Abha. There were also boasts of the involvement of sons of Asir and references to the ceremony at an online chatroom at www.alsaha.com, a popular Web site, according to two Saudi academics who closely monitor the site.
Amid all the conflicting accounts and sketchy information about the hijackers, what is certain, according to US investigators, is that the two Alshehri brothers were on board American Airlines Flight 11 when it left Boston and crashed into the north tower of the World Trade Center. And their friends Alnami and Alghamdi were both on board United Airlines Flight 93 when it left Newark and, apparently after a struggle inside the plane, plummeted into Stony Creek Township, Pa.