UPDATE: Flynn's lawyers weigh in on allegations against their client:
“Out of respect for the process of the various investigations regarding the 2016 campaign, we have intentionally avoided responding to every rumor or allegation raised in the media,” Flynn’s lawyers said in a statement Friday afternoon. “But today’s news cycle has brought allegations about General Flynn, ranging from kidnapping to bribery, that are so outrageous and prejudicial that we are making an exception to our usual rule: they are false.”
Flynn's lawyers decry series of Mueller-related news reports as 'false' (Politico)
The Wall Street Journal reveals Special Counsel Robert Mueller is looking into reports that Michael Flynn and his son met with Turkish officials at the 21 Club in NYC shortly before Donald Trump's inauguration to discuss a possible multimillion-dollar deal to "forcibly remove from the US a Muslim cleric wanted by Turkey."
CNN:
The discussions allegedly included how to transport Fethullah Gulen, a Muslim leader who [Turkish President Recep Tayyip] Erdogan has accused of being behind a failed military coup to overthrow him, on a private jet to the Turkish prison island of Imrali.
(...)
Former CIA Director James Woolsey told CNN in March about an earlier meeting in September 2016 where Flynn also met with representatives of the Turkish government and discussed potential ways to send a foe of Turkey's president back to face charges in that country.
Woolsey claims that those present discussed sending Gulen back to Turkey to face charges -- possibly outside the legal US extradition system.
Additionally, three people familiar with the probe said investigators are examining whether Flynn and other participants discussed a way to free a Turkish-Iranian gold trader, Reza Zarrab, who is jailed in the U.S. Zarrab is facing federal charges that he helped Iran skirt U.S. sanctions.
(...)
Rudy Giuliani, who was a top Trump campaign surrogate alongside Flynn, is part of Zarrab's defense team. The New York Times reported that Giuliani met with Erdoğan in late February and discussed an agreement under which Zarrab would be freed in exchange for Turkey's help furthering U.S. interests in the region.
Speaking to reporters after the meeting, Erdoğan said he had previously raised Zarrab's case with then-Vice President Joe Biden and suggested Preet Bharara, the U.S. attorney in Manhattan, was acting on behalf of supporters of Gülen, according to the Turkish newspaper Hürriyet. Trump fired Bharara this past March.
Full story: Mueller Probing Possible Deal Between Turks, Flynn During Presidential Transition (NBC News)
WSJ: Mueller probes Flynn role in plot to deliver cleric to Turkey (CNN)