"Charter schools are public schools," he said. "We follow the state curriculum."
But federal agencies - including the FBI and the Departments of Labor and Education - are investigating whether some charter school employees are kicking back part of their salaries to a Muslim movement founded by Gulen known as Hizmet, or Service, according to knowledgeable sources.
Unlike in Turkey, where Gulen's followers have been accused of pushing for an authoritarian Islamic state, there is no indication the American charter network has a religious agenda in the classroom.
Religious scholars consider the Gulen strain of Islam moderate, and the investigation has no link to terrorism. Rather, it is focused on whether hundreds of Turkish teachers, administrators, and other staffers employed under the H1B visa program are misusing taxpayer money.
Federal officials declined to comment on the nationwide inquiry, which is being coordinated by prosecutors in Pennsylvania's Middle District in Scranton. A former leader of the parents' group at the State College school confirmed that federal authorities had interviewed her.
Bekir Aksoy, who acts as Gulen's spokesman, said Friday that he knew nothing about charter schools or an investigation.
Aksoy, president of the Golden Generation Worship & Retreat Center in Saylorsburg, Pa., where Gulen lives, said Gulen, who is in his early 70s, "has no connection with any of the schools," although he might have inspired the people who founded them.
Another aim of the Gulen schools, a federal official said, is fostering goodwill toward Turkey, which is led by Recep Tayyip Erdogan, the pro-Islamic prime minister, whose government recently detained journalists after they alleged that Gulen followers were infiltrating security agencies.
Gulen schools are among the nation's largest users of the H1B visas. In 2009, the schools received government approvals for 684 visas - more than Google Inc. (440) but fewer than a technology powerhouse such as Intel Corp. (1,203).
The visas are used to attract foreign workers with math, science, and technology skills to jobs for which there are shortages of qualified American workers. Officials at some of the charter schools, which specialize in math and science, have said they needed to fill teaching spots with Turks, according to parents and former staffers.
Ruth Hocker, former president of the parents' group at the Young Scholars of Central Pennsylvania Charter School in State College, began asking questions when popular, certified American teachers were replaced by uncertified Turkish men who often spoke limited English and were paid higher salaries. Most were placed in math and science classes.
"They would tell us they couldn't find qualified American teachers," Hocker said.
That made no sense in Pennsylvania State University's hometown, she said: "They graduate here every year."
Other school parents described how uncertified teachers on H1B visas were moved from one charter school to another when their "emergency" teaching credentials expired and told of a pattern of sudden turnovers of Turkish business managers, administrators, and board members.
The charter school application that Truebright filed with the Philadelphia School District in 2005 mentioned that its founders helped start similar schools in Ohio, California, and Paterson, N.J.
Shana Kemp, a School District spokeswoman, said that the district had just learned Riza Ulker, Truebright's permanent CEO, was on extended sick leave and that it would look into that. She said district officials knew nothing about a federal investigation of these charter schools.
Further evidence of the ties comes from a disaffected former teacher from Turkey who told federal investigators that the Gulen Movement had divided the United States into five regions, according to knowledgeable sources. A general manager in each coordinates the activities of the schools and related foundations and cultural centers, he told authorities.
Ohio, California, and Texas have the largest numbers of Gulen-related schools. Ohio has 19, which are operated by Concept Schools Inc., and most are known as Horizon Science Academies. There are 14 in California operated by the Magnolia Foundation. Texas has 33 known as Harmony schools, run by the Cosmos Foundation.
In their investigation, federal authorities have obtained copies of several e-mails that indicate the charter schools are tied to Hizmet and may be controlled by it:
One activist sent an e-mail Aug. 30, 2007, to administrators at four schools and the president of Concept Schools in which he mentioned "Hizmet business" and several problems that needed to be addressed so that "Hizmet will not suffer."
And the disaffected teacher who described the five regions gave authorities a document called a tuzuk, which resembles a contract and prescribes how much money Turkish teachers are supposed to return to Hizmet.
State auditors in Ohio found that a number of schools had "illegally expended" public funding to pay legal, immigration, and air-travel fees for nonemployees and retained teachers who lacked proper licenses. Audited records from the Horizon Science Academy in Cincinnati in May 2009 also say that "for the period of time under audit, 47 percent (nine of 19) of the school's teachers were not properly licensed."
The same records show that the founder of Horizon Cincinnati was listed as the CEO of the school's management firm and as president of the school's property owner.
The American charter schools were a central part of Gulen's argument that won him a green card after the Department of Homeland Security ruled that he did not meet the qualifications of an "alien of extraordinary ability" to receive a special visa.
In a lawsuit Gulen filed in U.S. District Court in Philadelphia in 2007 challenging the denial, his attorneys wrote: "In his position as the founder and head of the Gulen Movement, Mr. Gulen has overseen the establishment of a conglomeration of schools throughout the world, in Europe, Central Asia, and the United States."
His attorneys also referred to a letter of support from a theology professor in Illinois who described Gulen as "a leader of award-winning schools for underserved children around the world, including many schools in the major cities in America."
On July 16, 2008, U.S. District Court Judge Stewart Dalzell ruled that Gulen met the requirements for a green card.
Hocker, the State College parent, said the current CEO had assured her the school had no ties to Gulen.
Rather, he told her that Gulen had inspired him to go into education and that Turkey "wanted to be known for teaching, the way you would think of India" for information technology, Hocker said.
But she noted that when the school's founding CEO disappeared, his successor arrived from the Buffalo Academy of Science, another Gulen school. The dean of academics came from a related school in New Jersey. Ulker, Truebright's, CEO, was one of the school's founders and is a board member.
"If you start looking at their names, you can connect them back to all the other charter schools and Gulen groups," Hocker said.
She later withdrew her three children over concerns about secrecy and finances.
A sister school - Young Scholars of Western Pennsylvania - is scheduled to open outside Pittsburgh in the fall.
(Young Scholars in State College and Western Pennsylvania are not connected to the Young Scholars Charter School in North Philadelphia.)
Truebright, at 926 W. Sedgley Ave., opened in 2007, enrolls seventh through 12th graders, and is about to hold its first graduation. Ninety percent of its students are African American. The school has met the academic standards of the federal No Child Left Behind Law the last two years.
Cidav, the acting CEO, came from the Harmony Science Academy in Austin, Texas. He said he could not comment on behalf of the school. He referred all questions to Ulker, who Cidav said had gone back to Turkey for a family emergency after Christmas and was not expected back until July. Board Chairman Baki Acikel did not respond to an e-mail request for comment.
Before Ulker's abrupt departure, he was involved in failed attempts to open charters in Camden and Allentown.
He also applied for Truebright to become one of the charter operators selected to take over failing Philadelphia schools as part of Superintendent Arlene C. Ackerman's Imagine 2014 initiative. In late December, Truebright was one of 10 organizations the district deemed "not qualified" for further consideration.
Claudio Gatti is the New York-based correspondent of Il Sole 24 Ore, the leading daily financial newspaper in Italy.
Contact staff writer Martha Woodall at 215-854-2789 or email@example.com.