Buzzfeed put out a fantastic long piece today detailing what Felix Sater and Michael Cohen were up to during the campaign with regards to the Trump Tower Moscow project. The players here are crazy, "former" GRU agents, multiple sanctioned Russian banks, Putin's personnel friends, Russian Mobsters* and all manor of other shady characters like Sater himself. Great read, unfortunately unlinkable here do to the language of Trumps pals and Trump himself in quote. And never forget that on the day of the third Republican presidential debate, Trump personally signed the letter of intent for this project while publicly denying any business activity with the Russians at all.
Google this: Trump Moscow: The Definitive Story Of How Trump’s Team Worked The Russian Deal During The Campaign
*like there is any distinction at this point between the Russian mafia, the GRU former or active and Russian government officials