The influential Muslim cleric lives quietly on a gated 26-acre compound in the Pocono Mountains, where he prays, works, meets admirers and watches from afar as terrorism accusations that have landed him on Turkey's most-wanted list unfold in court.
Rarely seen in public, Fethullah Gulen has long been one of Turkey's most important scholars, with multitudes of followers in his native country and around the world. More recently, Turkey's increasingly autocratic president, Recip Erdogan, has accused Gulen of plotting to overthrow the officially secular government from his Pennsylvania idyll some 5,000 miles away.
Gulen's supporters call the charge baseless and, so far, the U.S. has shown little inclination to send him back to Turkey to face a trial that began without him Jan. 6 and is expected to last several months.
If the reclusive leader worries about the possibility, he hasn't shared it with confidants, they say.
"He said that the United States has a long tradition of democracy and rule of law," said Y. Alp Aslandogan, who sees Gulen about once a week as president of the New York-based Alliance for Shared Values, a group that promotes Gulen's ideas. "They will see that these are politically oriented charges, and they will not allow Erdogan to spread his ambition into the United States."
Justice Department spokesman Peter Carr declined to comment on Gulen's case.
Gulen's followers run a loosely affiliated global network of charitable foundations, professional associations, businesses and other projects, including about 150 taxpayer-funded charter schools throughout the U.S. But details about Gulen's personal life and his ties to those ventures have long been murky, giving rise to suspicions about his motives.
Some of the U.S. schools have been investigated by the FBI amid allegations of financial mismanagement and visa fraud. One of the most explosive claims, leveled by a lawyer who is representing the Turkish government in a U.S. lawsuit against Gulen, is that the schools are importing Turkish teachers to identify impressionable students and indoctrinate them into Gulen's movement, sometimes called Hizmet, Turkish for "service."
Nobody associated with the U.S. schools has been charged, and there has been no public outcry from parents or students about teachers promoting Islam, Gulen's supporters say. In America, the schools are public and open to students of all faiths.
"Try proselytizing evangelical Christians in the center of Texas. See what happens," Aslandogan said. "Anybody who knows American society and climate today would know that's a ridiculous claim."
In any event, he said, Gulen has nothing to do with the schools' finances or operation.
Trained as an imam, or prayer leader, Gulen first gained notice in Turkey some 50 years ago, promoting a philosophy that blended a mystical form of Islam with staunch advocacy of democracy, education, science and interfaith dialogue. Supporters started 1,000 schools in more than 100 countries. In Turkey, they have run universities, hospitals, charities, a bank and a large media empire with newspapers and radio and TV stations.
But the extent of Gulen's reach is shrouded in such mystery that Loyola University Maryland sociologist Joshua Hendrick, who has studied and written about him, estimates his following at anywhere from 500,000 to 4 million people.
"I think deep down in the hearts of these people, they want to create a better world, a world of peace, a world of respect," said University of Houston sociologist Helen Rose Ebaugh, who traveled the world studying the Gulen movement's finances and aims. "I saw no indication they are after power or creating any kind of (Islamic) state."
In 2000, a year after traveling to the United States to seek medical treatment, Gulen was charged by Turkish authorities with leading an Islamist plot to overthrow the regime. He was acquitted after a trial in absentia.
Now, after a public split with Erdogan, he is facing another trial. This time, the Turkish government contends Gulen has been running a parallel state by getting his followers into key police and court positions to instigate a 2013 corruption probe that targeted people close to Erdogan.
Erdogan's government has branded the movement a "terror organization," though it is not known to have committed any acts of violence.
"The grain of truth, which we don't deny, is that yes, there are some sympathizers in every government institution. But to claim that there is a parallel entity, or there is a mastermind or puppeteer, is simply an empty claim," Aslandogan said.
A continent away, Gulen, who is in his mid-70s, lives like a monk on the grounds of the Golden Generation Worship & Retreat Center, an Islamic retreat founded by Turkish-Americans.
He spends hours a day in prayer and meditation and goes out rarely, mostly to see doctors for ailments that include heart disease and diabetes, according to Aslandogan. During a tour this week, an Associated Press reporter visited Gulen's book-lined living quarters, where shelves hold jars filled with soil from various regions of Turkey.
The reporter was unable to see the cleric. He was in another building on the compound and declined to be interviewed.