Omar Abdi Mohamed, a lanky, soft-spoken political refugee from war-ruined Somalia in East Africa, had been preaching the word of Islam in the United States for the past nine years. Two things make him unusual.

In January, U.S. immigration authorities arrested him, saying they suspected him of being a conduit for terrorist funds, federal court records show. At the time, he was on the payroll of Saudi Arabia's government.

Mohamed was one of 30 Saudi-financed preachers in this country. Each month, the Saudis paid $1,700 to the 44-year-old, who taught the Koran at a run-down Somali social center here. He worked with little supervision from Saudi religious authorities 8,000 miles away. In the late 1990s, he set up a small charity to help famine victims in Somalia, and that is how his trouble began.

The charity received $326,000 over three years from the Global Relief Foundation, a private Islamic charity based in Illinois. In October 2002, the U.S. Treasury Department designated Global Relief a terrorist-financing entity linked to al Qaeda.

The collision of Saudi missionary work and suspicions of terrorist financing in San Diego illustrates the perils and provocations of a multibillion-dollar effort by Saudi Arabia to spread its religion around the world. Mohamed worked on the front lines of that effort, a campaign to transform what outsiders call "Wahhabism," once a marginal and puritanical brand of Islam with few followers outside the Arabian Peninsula, into the dominant doctrine in the Islamic world. The campaign has created a vast infrastructure of both government-supported and private charities that at times has been exploited by violent jihadists -- among them Osama bin Laden.

Nearly three years after the devastating Sept. 11, 2001, attacks on the World Trade Center and the Pentagon, a number of Saudi-supported Islamic preachers, centers, charities and mosques remain under intense scrutiny. U.S. investigators continue to look into the tangled money trails leading from Saudi Arabia to its embassy in Washington and into dozens of American cities.

At the end of one trail is Mohamed. Another avenue of interest involves the global finances of the al Haramain Islamic Foundation, a large Saudi-government-supported charity set up to propagate Wahhabism and sometimes referred to as "the United Way of Saudi Arabia." Al Haramain, which has an office in Ashland, Ore., sent Mohamed $5,000.

The commission investigating the Sept. 11 attacks stated in its July report that al Qaeda had relied heavily on international charities to raise money, "particularly those with lax external oversight and ineffective internal controls such as the Saudi-based al Haramain Islamic Foundation." The report added that al Qaeda found "fertile fund-raising groups" in Saudi Arabia, "where extreme religious views are common and charitable giving was both essential to the culture and subject to very limited oversight."

The Saudis say they have taken more steps than any other country to crack down on terrorist financing. They say the problem is not with their religion but with a small minority of deviants.

The Saudi government has severed ties with Mohamed, who is charged only with immigration violations, but he insists he did nothing wrong. A hearing is set for Sept. 1 in San Diego. The terrorist suspicions against Mohamed appear to rest on financial transactions that raise questions but do not provide answers, court records show. Global Relief denies it funds terrorism.

The Saudis are also shutting al Haramain offices worldwide. In June, the Treasury Department put the charity's former head in Riyadh, Saudi Arabia, on its list of known supporters of terrorism for providing "financial, material and logistical support to the al Qaeda network."

Wahhabism arose in the mid-18th century in central Saudi Arabia. Mohammad Ibn Abdul Wahab sought to purify Islam and return it to its 7th-century roots. He preached doctrines based on a strict adherence to the literal word of the Koran. He opposed music and adornment, insisted that women be cloaked and disdained nonbelievers, even members of other Muslim sects.

Scholars of Islam find it difficult to precisely assess the impact of 40 years of Saudi missionary work on the United States' multi-ethnic Muslim community -- estimated at 6 million to 7 million. But survey data are suggestive.

The most comprehensive study, a survey of the 1,200 U.S. mosques undertaken in 2000 by four Muslim organizations, found that 2 million Muslims were "associated" with a mosque and that 70 percent of mosque leaders were generally favorable toward fundamentalist teachings, while 21 percent followed the stricter Wahhabi practices. The survey also found that the segregation of women for prayers was spreading, from half of the mosques in 1994 to two-thirds six years later.

John L. Esposito, a religion scholar at Georgetown University, said the Saudi theological efforts have resulted in "the export of a very exclusive brand of Islam into the Muslim community in the United States" that "tends to make them more isolationist in the society in which they live."

The Export of Islam

The worldwide export of Wahhabi Islam began in 1962, when Saudi Arabia's ruling Saud family founded the Muslim World League in Mecca to promote "Islamic solidarity." The Sauds were seeking to counter the fiery pan-Arab nationalism of Egyptian leader Gamal Abdel Nasser, who was calling for the Saudi monarchy to be overthrown.

The family also saw the export of Islam, which they call "Dawah," as a sacred duty. Their land was the birthplace of Islam and their kingdom host to the religion's two holiest mosques, in Mecca and Medina.

Western diplomats stationed in Riyadh liken the Sauds' fervor to the zeal of the United States' own fundamentalist sects. "For Saudi Arabia to stop Dawah would be a negation of itself," said Sherard Cowper-Coles, the British ambassador to the kingdom. "It would be like Bush telling Evangelical Christians to stop missionary work abroad."

In the 1960s, the kingdom was sparsely populated and still relatively poor. It had no trained foot soldiers to run the Muslim league. So the royal family enlisted scores of Egyptian teachers, scholars and imams belonging to the Muslim Brotherhood, a highly secretive movement of political activists dedicated to restoring Islamic rule over secular Arab societies.

By 1982, the Saud family was feeling threatened by the Islamic revolution begun by Shiite Muslim leader Ayatollah Khomeini in Iran and the extremism of some of its own citizens, who had temporarily seized the Grand Mosque in Mecca in 1979. Again, the family turned to Dawah.

King Fahd issued a directive that "no limits be put on expenditures for the propagation of Islam," according to Nawaf Obaid, a Saudi oil and security analyst. Saudi Arabia now had the money: Its oil revenue had skyrocketed after the 1973 oil embargo. King Fahd used the cash to build mosques, Islamic centers and schools by the thousands around the world. Over the next two decades, the kingdom established 200 Islamic colleges, 210 Islamic centers, 1,500 mosques and 2,000 schools for Muslim children in non-Islamic countries, according to King Fahd's personal Web site. In 1984, the king built a $130 million printing plant in Medina devoted to producing Saudi-approved translations of the Koran. By 2000, the kingdom had distributed 138 million copies worldwide.

Exactly how much has been spent to spread Wahhabism is unclear. David D. Aufhauser, a former Treasury Department general counsel, told a Senate committee in June that estimates went "north of $75 billion." Edward L. Morse, an oil analyst at Hess Energy Trading Co. in New York, said King Fahd tapped a special oil account that set aside revenue from as much as 200,000 barrels a day -- $1.8 billion a year at 1980s oil prices. Saudi oil expert Obaid confirmed such an account existed in the 1980s and 1990s but said it was recently closed.

Ministry's Far Reach

After the Persian Gulf War in 1991, radical elements in the kingdom and in the Muslim Brotherhood excoriated the Sauds for calling in the Americans to defend them. In response, King Fahd tightened control over the missionary-and-charity campaign and tried to purge it of Brotherhood influence, setting up a new Saudi-supervised charity, al Haramain.

As part of this effort, the Saudis created an Islamic affairs ministry in 1993 that was intended to be the key institution for exporting Wahhabism. The ministry, officially known as the Ministry of Islamic Affairs, Endowment, Call and Guidance, is led by Saleh Sheik, a direct descendant of Ibn Abdul Wahab.

The goal of moderating Brotherhood-like militancy was only partly successful. Saudi scholars and sources say the ministry has become a stronghold of zealots.

The Islamic affairs ministry is located in a nondescript concrete-and-glass structure in the Malaz district of Riyadh, near the city's old airport. There, in an interview at his office in March, Sheik said the ministry meets weekly to "coordinate the Islamic policies of the different ministries outside the country."

The ministry's outreach is formidable. It pays the salaries of 3,884 Wahhabi missionaries and preachers, who are six times as numerous as the 650 diplomats in Saudi Arabia's 77 embassies. Ministry officials in Africa and Asia often have had more money to dispense than Saudi ambassadors, according to several Saudi sources. The Islamic affairs officials also act as religious commissars, keeping tabs on the moral behavior of the kingdom's diplomats. In the United States, a 40-person Islamic Affairs Department established in the Saudi Embassy in Washington became something of an independent body, with little supervision from the often absent ambassador, Prince Bandar bin Sultan.

Sheik estimated the Islamic affairs ministry's budget at $530 million annually and said it goes almost entirely to pay the salaries of the more than 50,000 people on the ministry payroll. That figure does not include the hundreds of millions of dollars in personal contributions made by King Fahd and other senior Saudi princes to the cause of propagating Islam at home and abroad, according to a Saudi analyst who insisted on anonymity because of the sensitivity of the issue. The real total spent annually spreading Islam is between $2 billion and $2.5 billion, he said.

Sheik said his ministry "supervises" charities abroad to "make sure their funds go to the right places" and also provides religious books and scholars for Saudi-supported Islamic centers, schools and universities. But it has "no direct responsibility" for them, he said.

Sheik is the direct supervisor of one charity supported by the Saudi government, al Haramain, which added an entirely separate army of 3,000 missionaries to the 3,884 on the ministry payroll.

Al Haramain's annual budget, $40 million to $60 million, paid for mosques, schools, Korans, wells, food and Saudi-approved veils, as well as scores of health clinics and orphanages in some of the poorest corners of the world. It operated in 50 countries.

In October 1997, the charity established its first U.S. presence when it incorporated in Ashland, Ore. It listed as its board president Aqeel Abdulaziz Aqil, who had been general manager for the charity since its founding. He operated from the Riyadh headquarters.

Everything changed for al Haramain with the worldwide crackdown on terrorist funding that followed the Sept. 11 attacks. By March 2002, U.S. and Saudi authorities had designated al Haramain offices in Bosnia and Somalia as terrorist-supporting organizations that had diverted charitable money to al Qaeda and a suspected Somali terrorist group, Al Ittihad Al Islamiya.

Two years later, on Feb. 13, 2004, IRS officials raided the Ashland office, saying there was "probable cause" that two top al Haramain officers had violated U.S. currency laws and filed false tax returns to cover the transfer of money to Muslim rebels fighting in Chechnya. (U.S. authorities so far have brought no formal charges against those officers, and the Oregon office remains open.) Aqil was fired in January. Six months later, U.S. officials designated him a terrorist supporter because of his alleged contacts with the Somali group Al Ittihad, the same organization that Omar Abdi Mohamed in San Diego is suspected of aiding.

By then, 15 al Haramain branches had been shut down, including those in Indonesia, Kenya, Pakistan, Afghanistan, Albania and the Netherlands.

In his interview with a Washington Post reporter in March, Sheik defended the charity. His ministry's own investigation did not find "any major mistakes" by the charity's leadership, except by its director, Aqil.

"The mistakes of individuals should not be attributed to the whole institution," Sheik said.

In June, however, the Saudi government announced that al Haramain was being closed down and that the Islamic affairs ministry would be stripped of its role as the main overseer of missionary work. A government-run commission under the Foreign Ministry now has that responsibility.

But the commission does not oversee the three other major Saudi-based-and-financed charities -- the Muslim World League, the World Assembly of Muslim Youth and the International Islamic Relief Organization. Also independent of the commission is at least one private Saudi charity, al-Muntada al-Islami. The charity, based in London, works primarily in Africa and publishes an English-language Islamic monthly, Al-Jumuah, which is distributed in the United States.

These four Saudi charities recently formed a U.S.-based trade group, the Friends of Charities Association, and hired the Belew law firm in Washington to represent their interests.

In the United States, Saudi Arabia's infrastructure of preachers and money started as a bulwark against the spread into American mosques of radical Shiism, which surged after Khomeini deposed the shah of Iran.

"Many countries in the West asked Saudi Arabia to get involved in these [Islamic] centers because at that time Saudi Arabia was considered moderate," Saudi Foreign Minister Prince Saud Faisal said in an interview in March. The Americans "felt comfortable with the presence of the Saudis," he said.

Backed by Saudi money, this presence grew rapidly. King Fahd's Web site now lists 16 Islamic and cultural centers that the kingdom has helped finance in California, Missouri, Michigan, Illinois, New Jersey, New York, Ohio, Virginia and Maryland. The largest is the King Fahd Mosque in Culver City, a suburb of Los Angeles. The mosque, built with $8 million in private donations from the king and his son, Crown Prince Abdullah ibn Abdulaziz, was officially inaugurated in 1998 for 2,000 worshipers. It includes a Koranic school, an Islamic research center and a bookstore.

The Islamic Affairs Department at the Saudi Embassy in Washington spearheaded the campaign. At its height, the department had 35 to 40 diplomats and an annual budget of $8 million, according to a Saudi official.

In 1989, the Saudis also set up a high-powered Islamic learning center, the Institute of Islamic and Arabic Sciences in America, in Fairfax. The institute is an outpost of the Imam Muhammed Ibn Saud Islamic University in Riyadh, the main citadel for Wahhabi instruction.

The Islamic affairs ministry sent imams and itinerant preachers to the United States as well: As late as last year, it had 31 on its payroll, including Omar Abdi Mohamed in San Diego.

The ministry also flooded the American Muslim community with Saudi-published Korans and publications. "The great majority of books and magazines were authored by Saudi agencies," said Maher Hathout, chairman of the Islamic Center of Southern California in Los Angeles.

Hathout, an outspoken critic of Wahhabism, said the result was the increasing isolation of women in American mosques starting in the 1980s. "Mosques became gender-segregated, which didn't make any sense at all," he said.

The commentary accompanying the Saudi-published Koran, Hathout said, was "very alien to the spirit of tolerance" in U.S. society. "This may have sense over there [in Saudi Arabia] but doesn't make any sense here," he said.

In the 1990s, a "sharp debate" raged in U.S. mosques over Saudi fundamentalism, said Ihsan Bagby, chief author of the study "The Mosque in America." Radical "nongovernmental Saudi sheiks" became very active in pushing a far more militant brand of Wahhabism than the government-appointed imams, Bagby said. These radicals cultivated American Muslims, who used Saudi money to build their own mosques, he said.

In May 2003, the State Department refused reentry to the chief imam of the King Fahd Mosque in Culver City, Fahad al Thumairy, who also was a Saudi diplomat at the consulate in Los Angeles. The Sept. 11 commission report later said the State Department had determined "he might be connected with terrorist activity."

The report also said that two of the Sept. 11 hijackers, Nawaf Alhazmi and Khalid Almihdhar, "spent time at the King Fahd mosque and made some acquaintances there." Al Thumairy, who reportedly led an "extremist faction" at the mosque, denied knowing the two hijackers. While his denial was "somewhat suspect," the report said there was no evidence connecting him to the hijackers.

Last December, the State Department ended the practice of allowing religious scholars and missionaries to work here on Saudi diplomatic passports, forcing at least 24 out. The best-known deportee was Jaafar Idris, a Sudanese scholar well known in the Islamic world and founder of the American Open University, based in Alexandria, which in 2002 had 540 registered students pursuing undergraduate and graduate degrees in Islamic studies.

Also crippled by the crackdown was the Institute for Islamic and Arabic Sciences. Eleven of its scholars on diplomatic passports were ordered to leave. In early July, dozens of FBI, customs and IRS agents raided the institute's premises and questioned its six remaining non-Saudi teachers.

Late last year, the Saudi Embassy in Washington dissolved its Islamic Affairs Department, reducing the number of diplomats dealing with religious issues to one. The embassy also stopped distributing the Koran in the United States. At the same time, the Ministry of Islamic Affairs began reviewing its 31 missionaries and preachers in the United States. As of March, six had been fired.

The only one to go to jail was Omar Abdi Mohamed, the Somali teacher in San Diego.

Suspected Ties to Terrorism

A trader in hides, livestock and incense, Mohamed regularly visited Saudi Arabia in the 1980s. During one of his trips, he said, he was recruited by the kingdom's religious authorities in Mecca after being questioned about his knowledge of the Koran. In Somalia, preaching became a sideline for him, he said.

In 1989, Mohamed was jailed and tortured by the Somali military, which suspected him of involvement with the political opposition, according to statements Mohamed later made on his immigration documents. The following year, as Somalia degenerated into civil war, he was freed and fled to Canada. Five years later, he made his way to San Diego.

He had been recruited by a San Diego mosque to teach the Koran and Arabic to Somali children, he said later. He entered the United States on a religious worker's visa and received legal permanent resident status. The U.S. government would later say he never worked at the mosque that sponsored his visa.

Instead, Mohamed founded a small Koranic "school," actually just one room inside a shabby two-story Somali civic center in a section of City Heights nicknamed "Little Mogadishu," after Somalia's capital. Mohamed also worked part time as a social counselor for Somali children at a public school, which paid him $1,000 a month.

In 1997, Mohamed set up his charity, the Western Somali Relief Agency, to send money to Somalis facing famine in the Ogaden region of eastern Ethiopia. Over the next four years, the agency received $326,000 from the Global Relief Foundation, court documents show.

In April 2000, Mohamed applied for U.S. citizenship. He had an interview with U.S. immigration officials in May 2002. By then, the Sept. 11 attacks had made U.S. officials wary of any Muslims applying for citizenship. Mohamed's background was checked, and the immigration officers asked him pointed questions about his relief agency and the money that had circulated through it, court documents show.

He did not tell them initially that he was being paid by the Saudis or that he had received money from Global Relief and al Haramain, the records show.

In January, he was called in for a second interview. Afterward, he was arrested and charged with making multiple false statements.

"You've received funding well over $200,000 from Global Relief," said Steve Schultz, an immigration officer, according to a transcript of Mohamed's interview. "They were shut down because they were providing aid to terrorism. Okay, we think you're involved in that."

In October 2002, the Treasury Department designated Global Relief, based in Bridgeview, Ill., a terrorist-linked organization because it "has provided assistance to Osama Bin Laden, the al Qaeda Network and other known terrorist groups," a Treasury news release stated.

Rabih Haddad, the co-founder of Global Relief, had belonged to an organization that was a precursor to al Qaeda. Charity officials had also had multiple contacts with the Taliban government in Afghanistan and bin Laden's personal secretary, who was convicted of participating in the 1998 bombings of the U.S. embassies in Kenya and Tanzania.

The Treasury Department release stated that photographs found in a trash bin outside Global Relief's office in Illinois depicted armed fighters and a shipment of sophisticated communications equipment worth $120,000. Videotapes stocked by Global Relief glorified armed jihad. "God equated martyrdom through JIHAD with supplying funds for the JIHAD effort," a 1995 Global Relief Foundation pamphlet stated. "All contributions should be mailed to: GRF."

U.S. investigators have been unable to track all of the money Mohamed received from Global Relief. The bulk of it went in checks written to Dahab Shil, an informal money transmitter in Chicago known among Muslims as a hawala. The 65 checks to Dahab Shil range from $370 to $60,000, according to court documents.

Mohamed said the money went to various local charities and tribal chiefs in the Ethiopian Ogaden. Transcripts of his interviews show U.S. officials suspect that some of it went to Al Ittihad Al Islamiya, the Somali terrorist group that the head of al Haramain has also been accused of dealing with.

During an interview in May at the federal prison in Otay Mesa, 15 miles south of San Diego, Mohamed insisted he was not a Wahhabi extremist, just a Muslim. He denied ever having contacts with Al Ittihad. With the loss of his $1,700 monthly stipend, his wife and six children live on a monthly welfare check of $1,178.

Research editor Margot Williams and researcher Alice Crites contributed to this report.

Since the Sept. 11 attacks, a number of Saudi-supported Islamic mosques -- such as the King Fahd Mosque, left -- have been under scrutiny.

Bilan Abdul Hasan prays at the King Fahd Mosque in Culver City, Calif. The mosque was built with $8 million in donations from the king and his son.At Prince Sultan school in Riyadh, Saudi Arabia, the students recite verses from the Koran four times a week to learn about Islam.Saleh Sheik leads the Islamic affairs ministry that was intended to be the key institution for exporting Islam.