FALLS CHURCH, Va. (AP) — Federal prosecutors on Monday dropped charges against Bijan Kian, a onetime business partner of former National Security Adviser Michael Flynn who had been accused of acting as an unregistered agent of the Turkish government.

Monday's decision ends a five-year legal saga for Kian, whose case received significant attention when he was charged in 2018 as a spinoff from special counsel Robert Mueller’s investigation of Russian election interference.

Prosecutors alleged that Kian and Flynn, who were partners in an entity called the Flynn Intel Group, were acting at Turkey’s behest when they undertook a project to discredit exiled Turkish cleric Fethullah Gulen. Gulen has been sought for extradition from the U.S. by Turkish President Recep Tayyip Erdogan, who blames Gulen for an attempted coup in that country.

Flynn wrote a November 2016 op-ed piece, shortly before he was named to be then-President-elect Donald Trump's national security adviser, comparing Gulen to former Iranian leader Ayatollah Ruhollah Khomeini. Prosecutors said Turkey directed the effort and pointed to a series of irregular payments flowing back and forth between Kian and an alleged Turkish middleman, businessman Kamal Alptekin.

Kian was initially convicted in a 2019 jury trial. But Judge Anthony Trenga, who heard the case, later tossed out the conviction and ordered a not guilty verdict, saying there was no substantial evidence that he agreed to operate at the Turkish government's direction or that Alptekin was an intermediary for Turkey.

The government's case had been thrown into disarray at the outset of trial when it decided not to call Flynn, who was expected to be prosecutors' star witness. Flynn acknowledged in a separate case that he made false statements about work he performed that benefited Turkey; he had hoped at one point that cooperating with prosecutors in Kian’s case would help him receive a lighter sentence in his own case. But he later sought to rescind his guilty plea and stopped cooperating.

The government appealed Trenga's decision, and the 4th U.S. Circuit Court of Appeals sent the case back to Trenga to reinstate the conviction. The appeals court left only a narrow path for Trenga to order a new trial if he could outline in detail why the evidence failed to support a conviction.

Last year Trenga issued a 51-page ruling ordering that new trial. Among other factors, he cited evidence that an actual conspiracy involved Flynn and Alptekin, with Kian excluded from the arrangement.

Prosecutors had initially seemed prepared to pursue a new trial, which was scheduled to begin in October. A spokeswoman for the U.S. Attorney's Office in the Eastern District of Virginia declined to comment on why prosecutors decided to drop the case.

Mark MacDougall, one of the lawyers for Kian — whose full last name is Rafiekian — said in a written statement that his client is grateful that the judge set aside the jury's verdict.

“The Justice Department has finally conceded that this case should never have been indicted. Mr. Rafiekian has been the target of baseless federal prosecution for the past five years, only because he made the poor decision to be in business with Michael Flynn,” MacDougall said.

Flynn, who received a presidential pardon in 2020, became a chief promoter of Trump's efforts to overturn the results of the 2020 election.