Federal investigators are now examining a possible meeting between former disgraced National Security Adviser Micheal Flynn and senior Turkish officials that took place mere weeks before President Donald Trump was sworn into office about a potential deal in which Flynn would receive payment for supervising pro-Ankara directives while part of the White House, say sources familiar with the investigation.

According to sources close to Special Counsel Robert Mueller’s investigation into Russian interference in the U.S. presidential election, investigators recently questioned witnesses over an alleged meeting between Flynn and senior Turkish officials in December 2016. Four people familiar with the case say Mueller is looking to see whether Flynn discussed orchestrating a return of a chef rival of Turkish President Recep Erdogan who currently resides in the U.S.

Mueller is also concerned with whether or not Flynn discussed ways in which to free a Turkish-Iranian gold trader, Reza Zarrab, who is currently jailed in the U.S. and is facing federal charges for allegedly assisting Iran in sidestepping U.S. sanctions.

Investigators are looking to see whether the deals, if successful, brokered between Flynn and Turkish officials would have resulted in the secret payment of millions to Flynn personally.

The alleged meeting took place at the 21 Club, an upscale restaurant in New York City just blocks from Trump Tower, sources say it was there that Flynn was offered upwards of $15 million in order to carry out the pro-Ankara initiatives.

Flynn was, at the time, serving on the Trump transition team. It still remains unclear to investigators just how Flynn could have carried out the deals. However, any deal in which a government official is offered money in exchange for services constitutes multiple federal crimes and is considered as a bribe.

Special Counsel Mueller’s probe is also looking into Flynn’s son, Michael G. Flynn for his possible involvement as well. Michael G. Flynn works for his father’s lobbying group, Flynn Intel Corp.

Michael Flynn was fired in February a mere 24 days into the Trump presidency for misleading Vice President Mike Pence as well as other officials concerning his dealings with the Russian ambassador.

Last week, NBC reported that federal investigators have gathered enough evidence to bring charges against Michael Flynn. The Grand Jury is continuing to interview witnesses close to Flynn in order to further its investigation.

President Erdogan of Turkey has pressed U.S. officials in the past to extradite Fethullah Gulen, who he blames for the attempted coup in July of 2016, and has also repeatedly raised questions into Zarrab’s case to officials in the U.S. as well. The New York Times reported that former Mayor of New York City Rudy Giuliani had also previously met with Erdogan in February to discuss the return of Zarrab in exchange for furthering U.S. interests in the region.