There's a long and informative piece in The New Republic entitled "Trump's Russian Laundromat" that provides details into Putin loyalist and con artist Donald "Rump" Trump's long-standing relationships with dirty money from Russia, money that was obtained in Russia through fraud, corruption and extortion by a Kremlin-connected band of mobsters and oligarchs. After the collapse of the Soviet Union, the country's criminal enterprises merged with elements of the Russian intelligence services and military to loot the public treasury and to bring major industries under their control in a vast criminal kleptocracy. Looking for places outside of Russia to launder their money, they looked to real estate in the U.S., and specifically to New York City. There they found a floundering, narcissistic Rump, who was always short on cash and looking for investors, after American banks increasingly turned him away. That began the saga of Russian money and Rump. An excerpt from the piece (which you must read):
"...even without an investigation by Congress or a special prosecutor, there is much we already know about the president’s debt to Russia. A review of the public record reveals a clear and disturbing pattern: Trump owes much of his business success, and by extension his presidency, to a flow of highly suspicious money from Russia. Over the past three decades, at least 13 people with known or alleged links to Russian mobsters or oligarchs have owned, lived in, and even run criminal activities out of Trump Tower and other Trump properties. Many used his apartments and casinos to launder untold millions in dirty money. Some ran a worldwide high-stakes gambling ring out of Trump Tower—in a unit directly below one owned by Trump. Others provided Trump with lucrative branding deals that required no investment on his part. Taken together, the flow of money from Russia provided Trump with a crucial infusion of financing that helped rescue his empire from ruin, burnish his image, and launch his career in television and politics. 'They saved his bacon,' says Kenneth McCallion, a former assistant U.S. attorney in the Reagan administration who investigated ties between organized crime and Trump’s developments in the 1980s." (emphasis added)There's little doubt that Special Counsel Robert Mueller, with assistance from the U.S. Attorney for the Southern Manhattan district, is fully aware of this history, which would explain Rump's fierce loyalty to the Kremlin. After all, "they saved his bacon."
UPDATE: As if on cue, the mysterious eighth person sitting in on Junior's collusion meeting with the Russians in June 2016 was a Russian-American who engaged in, shall we say, washing cash.