NEW YORK (AP) — U.S. prosecutors are seeking leniency at next-week’s sentencing of a Turkish-Iranian businessman who admitted to helping Iranians and their government evade sanctions and who provided key testimony at a 2017 corruption trial that strained relations between the U.S. and Turkey.

The prosecutors said Monday in a sentencing memorandum to a New York federal judge that international gold trader Reza Zarrab provided substantial help to the U.S. when he revealed paying millions of dollars in bribes to government and banking officials in Turkey and provided key testimony at the December 2017 trial.

His testimony preceded the conviction of Turkish banker Mehmet Hakan Atilla and a sentence of over two years in prison for the banker. After the trial, Turkey President Recep Tayyip Erdogan called the verdict “scandalous.”

In a presentence memorandum, prosecutors wrote that Zarrab’s October 2017 guilty plea to conspiracy, bank fraud and money laundering charges and the cooperation that followed had been “truthful, complete and reliable” and significant, useful and timely. They also noted that he had suffered “danger or risk” as a result of his help.

During a week on the witness stand at the 2017 trial, Zarrab said he was attacked in prison by a knife-wielding fellow inmate who claimed he was told to kill him for cooperating with U.S. authorities.

In their memorandum Monday, prosecutors referenced the threat, which resulted in Zarrab being moved from prison and into FBI custody.

According to prosecutors, the inmate at the Metropolitan Detention Center in Brooklyn who threatened Zarrab told him that he would be killed because he was cooperating against “big people in Turkey.”

Prosecutors also said that the government of Turkey imposed broad freezes and seizures of Zarrab’s assets after he began cooperating.

The lengthy delay for Zarrab’s sentencing is not uncommon in a complex prosecution that carried the potential for multiple trials in which Zarrab’s testimony might be necessary.

Last month, Judge Richard M. Berman in Manhattan approved the dismissal of a criminal case the U.S. government had brought against Halkbank, a state-owned bank in Turkey. The U.S. government’s request to drop the charges came amid warm ties between Erdogan and President Donald Trump.

After meeting with Trump last year at the NATO summit in The Hague, Erdogan told reporters that the U.S. president is quick to return his calls, an anecdote that signaled their close ties.

“With my friend Trump, we are opening the door to a new era in Turkish‑American relations,” said Erdogan, who has been president of Turkey for 13 years.

Larry Neumeister, The Associated Press