Turkey has detained 17 suspects in an investigation into Turkish-Iranian gold trader Reza Zarrab, who pled guilty and testifies as a witness in the trial of Mehmet Hakan Atilla, deputy CEO of state-owned Halkbank, in the Iran sanctions trial in New York, reports said Tuesday.

Turkish media reported Friday that the Istanbul Public Prosecutor's Office launched an investigation to confiscate Zarrab and his close relatives' assets over charges of espionage.

During the probe, three of Zarrab's employees, Sinem Arslan, Regaip Akol and Mustafa Hacısalihoğlu, were detained, and manuscripts containing evidence were seized. In the documents, Zarrab reportedly instructed his employees to discuss with his lawyers a possible way of moving to Dubai after he would be set free by the U.S. court following a collaboration with the prosecutors of the Iran sanctions case.

On Tuesday, police conducted a new investigation and detained another 14 people.

Zarrab last month accepted all the U.S. charges against him, including the violation of now-lifted U.S. sanctions against Iran, money laundering and other charges and agreed to cooperate as a witness against Mehmet Hakan Atilla, the former deputy CEO of Turkey's state-run lender Halkbank.

Zarrab, 34, was arrested by U.S. authorities in March 2016 on suspicion of taking part in the alleged sanctions-busting scam but is now cooperating with the authorities in an apparent plea bargain.

Turkish officials have repeatedly argued that the U.S. case is a bid by fugitive leader of Gülenist Terror Group (FETÖ) Fetullah Gülen to besmirch Erdoğan and Turkey.

"The case is not a plot against America, it's a plot against Turkey," said Erdoğan in a speech Tuesday.

"The case has nothing to do with law, justice or trade, it's an acrobatic spectacle."

Since Zarrab became a witness, deputy chief executive of Turkish lender Halkbank Mehmet Hakan Atilla has become the lone defendant in the dock accused of violating sanctions, bribery and money laundering.

Zarrab testified that he bribed a former Turkish economy minister Zafer Çağlayan and was involved in the multibillion-dollar gold-for-oil scheme.

On Wednesday, a letter of the defense cited a September 2016 jailhouse call in which Zarrab said he needed to lie in "'in order to get out or to get a reduced sentence." Defense attorney Victor Rocco has raised questions over Zarrab's credibility, suggesting he made a deal to get out of jail free.

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

The judge and the prosecutor in the Zarrab case were linked to the Gülenist Terror Group (FETÖ), led by fugitive preacher Fetullah Gülen, who has been living in self-imposed exile in Pennsylvania since 1999. Turkey accuses FETÖ of being behind the coup attempt on July 15, 2016, in which 250 people were killed and over 2,200 were injured.