"He learned the basics of Islam here, such as how to pray," said 23-year-old Abdullah Nana. "He had a thirst for knowledge."

Walker was soon trying to memorize the entire Koran.

More Strident Islamic Voices

According to the Nanas, Walker's newfound fascination led him to visit two mosques in San Francisco, Masjid Darussalam and the San Francisco Islamic Center. It was there that his dedication broadened, exposing him to new--and more strident--brands of Islam.

Majid Darussalam is a third-floor mosque on Jones Street, just up the block from Market Street, amid the strip clubs and soup kitchens in a gritty section of the city.

Neither Amatullah Al-Marwani, the executive secretary of the mosque, nor her husband, Mohammed, say they have heard from anyone who remembers Walker visiting the place.

"We don't talk of war here, no talk of anything violent," Mohammed said. "We only want to know Allah and to pray.

"Whatever happened to push him to the Taliban, I guarantee it didn't happen here," Mohammed said. "You will see it happened in Pakistan. It must have been so."

It might have been here, however, that Walker first heard the fiery Islamic rhetoric that is preached at many U.S. mosques--especially before Sept. 11. "Young people can get carried away when they hear all this angry rhetoric about Zionism and America and injustice," said one Muslim man who has visited the Jones Street mosque and was offended by the anti-American message he heard. "We should stop importing these imams (Muslim preachers) from the Middle East." The shelves of the mosque--as at many Muslim centers--contain an array of writings, peaceful and otherwise. One book in stock this week, for instance, raves of "The indomitable spirit of Jihad," while another alongside it preaches of "Islam and Universal Peace."

Bernal Heights Mosque

Walker's sojourn to Pakistan may have been inspired by his visit to the second, smaller San Francisco mosque, on Crescent Street in Bernal Heights. That Islamic center is known in Bay Area Muslim circles as the local headquarters for tabligh jamaat, the Islamic revival movement.

"They come out of Pakistan and are kind of like Muslim evangelists," said one Muslim woman familiar with various Bay Area mosques. "They look for wayward Muslims and try to get them back on track."

But the woman, who asked that her name not be used, disagreed with some who described the tabligh jamaat as a recruiting group for militant movements. "They are not political," she said. "They are very peaceful."

Abdul Khalid, standing in the entry hall to the modest Crescent Street building, vigorously agreed, saying his mosque has nothing to do with Walker, the Taliban or Osama bin Laden.

"There is no politics here, no aggression," he said. "We are just spiritual."

Convention in Santa Clara

Ephrahim Nana said that both his son and Walker were influenced by the teachings of tabligh jamaat, which sponsors a variety of spiritual retreat programs--so much so that Walker attended a large annual convention of tabligh jamaat members in Santa Clara before he headed off to Pakistan. "They encourage people to spend a weekend in the path of Allah, or 40 days or four months on the path," he said. "Their message is that religious guidance doesn't come without sacrifice. One should sacrifice time and money in the name of Allah."

"Tabligh" means conveying the faith of Islam. Members travel from city to city, visiting mosques and knocking on doors of local Muslims, encouraging them to strengthen their faith.

Another man familiar with the movement, who asked that his name not be used, said the tabligh jamaat followers are sympathetic to the fundamentalist form of Islam practiced by the Taliban and by the Wahhabi sect that controls Saudia Arabia.

"They form the bedrock for extremism," he said. "Their whole aim in life is to grow a long beard and visit other communities and proclaim that Islam is the only valid faith."

Nana denied that the movement was "extremist," but he said it is likely that Walker's experience with tabligh jamaat may have inspired him to go to study in Pakistan.

"Whoever he met in Pakistan changed his direction, triggered him to the next level," Nana said.

Yemen Connection

Walker's explorations into Islam, San Francisco-style, may have also led him to Yemen.

Many of those who come to daily prayers at the Jones Street mosque are from that nation, which in 1998 became the first stop on John Walker's international Islamic odyssey.

He went to Yemen, friends said, because Yemeni Arabic is closest to the "pure" form used in the Koran. And Mohammed Al-Marwani of the Jones Street mosque pointed out that entry into Yemen is easier than many other Middle Eastern countries, "so it would make perfect sense that someone like him, wanting to study the Koran overseas, would go there."