Reza Zarrab Reza Zarrab.

A Turkish gold trader who pleaded guilty to evading U.S. sanctions is set on Wednesday to take the stand as a prosecution witness in the trial for his co-defendant.

Prosecutors confirmed on Tuesday that Reza Zarrab, 34, has pleaded guilty, according to media reports, ending weeks of uncertainty as to whether Zarrab was still participating in the case and in what capacity.

Zarrab, a dual citizen of Turkey and Iran, will testify against Mehmet Atilla, 47, who served as deputy CEO of one of Turkey’s largest state-owned banks in a case that has strained relations between the United States and Turkey.

The superseding information against Zarrab, which was filed on Oct. 16 and was unsealed on Tuesday, states that he was charged with conspiracy to defraud the United States, conspiracy to violate the International Emergency Economic Powers Act, bank fraud, conspiracy to commit bank fraud, money laundering and a related conspiracy charge.

He was also charged with one count of conspiracy to commit bribery and to possess contraband at a federal detention center for allegedly in July offering a bribe to corrections staff to smuggle in cellphones and alcohol.

Assistant U.S. Attorney David Denton said during opening statements that Zarrab would “tell the inside story and expose the truth behind all those elaborate lies” told by Atilla, according to The Associated Press.

But Victor Rocco of Herrick Feinstein, one of Atilla’s lawyers, retorted that Zarrab is testifying against Atilla so “he can buy freedom, a shortcut back to his lavish life with the rich and famous” and questioned the now-witness’ credibility.

Also on Tuesday, U.S. District Judge Richard Berman of the Southern District of New York denied a request by Atilla’s lawyers to delay the trial by an additional two weeks to allow them to process what they described as a “bombardment of new evidence” turned over by the prosecution on the eve of trial.

Assistant U.S. Attorneys Michael Lockard and Sidhardha Kamaraju and Special Assistant U.S. Attorney Dean Sovolos are also prosecuting the case.

In addition to Rocco, Atilla’s defense team includes Cathy Fleming and Robert Fettweis of the law firm Fleming.Ruvoldt.