A senior U.S. official confirmed on Friday that U.S. authorities have received a number of Turkish extradition requests for Pennsylvania-based fugitive former imam Fethullah Gülen, the alleged mastermind of the failed putsch, based on criminal activities that predate the coup.

On Tuesday, State Department spokesman Mark Toner confirmed that Obama administration says it has received a formal extradition request from Turkey for Gülen and is now considering the merits of the request.

Turkish officials told Daily Sabah last month that Turkey submitted four extradition requests for Gülen which detail at length the formal charges against Gülen. The files include two arrest warrants issued by the 14th Central Criminal Court in Istanbul, another from Bursa's 2nd Central Criminal Court and one from a magistrate judge at the request of Ankara's chief prosecutor. The charges against Gülen include embezzlement, aggravated fraud, the forging of official documents and violations of the right to privacy.

A senior official in the American administration, whose identity cannot be revealed according to White House protocol, said in parallel with a senior Turkish official that an additional extradition request for Gülen based on the coup has not yet been submitted. Turkish officials said that Turkey would eventually file the request once the legal process in Turkey has been finalized. The Turkish government cannot hand over the documents on Gülen's role in the coup until Turkish prosecutors complete their investigation into the matter and a Turkish court finds it appropriate. A Turkish official, speaking on condition of anonymity, said: "We are still trying to figure out exactly what happened. We simply can't submit evidences regarding Gülen immediately after the coup. That was of course legally and reasonably impossible."

The senior American official, whose identity cannot be revealed according to White House protocol, said the experts at the Department of Justice were reviewing – with the help of Turkish counterparts – all of the evidence provided by Turkish authorities to make sure that they understand the allegations. "If they ask for clarification and additional evidence, then in the coming days, we are going to have a term out in Turkey to help drill down on some of these allegations," the official said.

U.S. as well as Turkish officials expect that the extradition process will take a long time. Some experts say it could take two years or more. Turkish officials want their American counterparts to quickly pass the extradition files to the courts and at the least place Gülen under pre-trial detention.

The Turkish public overwhelmingly believes that the U.S. must have had something to do with the coup, not least because Gülen resides in Pennsylvania. U.S. Vice President Joe Biden will visit Turkey on Aug. 24, seeking to repair bilateral relations, damaged most recently due to the failed coup and the disagreements over the PKK terrorist organization's Syrian wing, the Democratic Union Party (PYD), which the U.S. perceives as a formidable ally against the DAESH terrorist organization, while Turkey considers it a terrorist organization. Biden will meet President Recep Tayyip Erdoğan and Prime Minister Binali Yıldırım to discuss Turkish-American cooperation over a range of issues, including DAESH and regional problems. The American official said that during his trip, Biden will pay his respects to the brave Turkish citizens who defended Turkish democracy. The official said,"The vice president will also reaffirm that the United States is doing everything we can to support Turkey's ongoing efforts to hold accountable those responsible for the coup attempt, while ensuring that the rule of law is respected during this process." Biden will leave Ankara on the evening of Aug. 24.