Questions have been raised about the impartiality of Mark Dubowitz, chairman of the U.S.-based think tank Foundation for Defense of Democracies, and its senior vice chairman, Jonathan Schanzer, as expert witnesses in the ongoing Zarrab case over their previous comments on the Turkish government and its president.

In June, Dubowitz's name was mentioned in leaked emails of Yousef Al- Otaiba, the United Arab Emirates' ambassador to the United States. The leaks included a proposed agenda of a meeting between the UAE government and the FDD – which is funded by pro-Israel billionaire Sheldon Adelson, an ally of Israeli Prime Minister Benjamin Netanyahu – on June 11-14, in which the attendees were set to discuss Turkey, Qatar and the Muslim Brotherhood.

The attendees, including FDD CEO Mark Dubowitz, Hannah and Jonathan Schanzer, FDD vice president for research, were expected to discuss issues like "Implications of Erdoğan's executive presidency," "Erdoğan's regional role and ambitions" and "Role of Islamism in Erdogan's policies and goals."

Otaiba was said to enjoy close relationship with FDD, together "trying to develop common policies against Turkey and Qatar."

Dubowitz's tweets following the July 15 coup attempt in Turkey, which said the coup attempt was conducted against "a regime destroying democracy," were also a source of concern in Turkey.

Dubowitz also wrote a seven-page Iran policy memo to Trump's National Security Council shortly after his inauguration, proposing to use Cold War anti-communist tactics, including the Reagan administration's support of the Polish "Solidarity" labor movement, which helped to fracture Eastern European communism.

Meanwhile, other witnesses named in the Zarrab case strengthened the Turkish government's claim that the trial was politically motivated.

Osman Zeki Canıtez – a former bank auditor for whom Turkey has issued an arrest warrant over links to the Gülenist Terror Group (FETÖ) as part of Istanbul Public Prosecutor Office's probe into the December 2013 judicial coup bid – is now one of the witnesses in the Atilla case.

Canıtez has also been identified as a user of ByLock, an app allegedly used by FETÖ members during last year's deadly defeated coup.

He is furthermore accused of bringing Atilla case "documents and evidence illegally from Turkey."

Canıtez will now stand as a witness in the case based on these documents, and it is expected he will appear before the court during the trial.

Former Republican People's Party (CHP) lawmaker Aykan Erdemir, too, is on the witness list in the Atilla case.

An arrest warrant is also out for Erdemir in Turkey.

Erdemir has rejected Istanbul Chief Public Prosecutor Office's claims about him in a written statement and said the charges against him are spurious.

Istanbul Chief Public Prosecutor's Office accuses Erdemir of "conducting acts that link the Turkish Republic with terror over fake evidence."

Erdemir is also accused of playing an important role in the meeting between a CHP delegation and administrators of some of FETÖ's most important organizations in the U.S. – the Rumi Forum and Turkic American Alliance – during the CHP delegation's U.S. visit in 2013.

He participated as a speaker to a roundtable meeting of the Rumi Forum, as well.

Erdemir's "fierce criticism against Turkish foreign policy" during a panel in Georgetown University in March last year, where FETÖ fugitive Emre Uslu was also present, likewise drew strong negative reaction.

Turkish-Iranian gold trader Reza Zarrab was arrested in Miami in March 2016 upon his entry in the U.S. for allegedly evading a U.S.-imposed sanction on Iran, lifted three months before his arrest, with multiple money transfers.

Officials in Turkey have argued that the case has been turned into a political move against Ankara.

Turkey's claims were proved after the judge overseeing the Zarrab case was linked to the Gülenist Terror Group (FETÖ), led by fugitive preacher Fetullah Gülen, who has lived in a self-imposed exile in Pennsylvania since 1999.

The Turkish government has accused the group of exploiting the case by illegally obtaining and fabricating evidence, including wiretap records done by now-sacked FETÖ-linked police officers.

Ankara says the so-called "evidence" was illegal for a court to use under U.S. law, which requires that any piece of evidence must be obtained through legal means.

Zarrab has pleaded guilty and testified as the prosecution's key witness at the U.S. trial of a banker on charges the two of them violated economic sanctions against Iran, ending weeks of speculation in a case that has strained relations between the U.S. and Turkey.

The revelation came Tuesday as a defense lawyer asked for a two-week delay of the New York City trial of Mehmet Hakan Atilla, deputy CEO of Halkbank, saying he needed time to prepare for Zarrabtarget="_blank"'>