For Donald Trump, there was the purchase of the $12.6 million Scottish estate and the $79.7 million for golf courses in the United Kingdom, not to mention the $16.2 million for the Northern Virginia Winery. All in cash.

For Michael Cohen, it was the lucrative day in 2014 when he sold four Manhattan buildings for $32 million—three times what he’d paid for them less than three years before.

Recent days have been filled with a seeming tidal wave of fresh revelations from the spiraling investigation around Donald Trump’s ties to Russia, particularly around suspicious financial transactions involving Trump fixer Michael Cohen, who appears to have used the same shell company LLC to pay hush money to porn star Stormy Daniels, collect six- and seven-figure consulting deals from companies like AT&T and Novartis, and receive payments from a company with close ties to oligarch Viktor Vekselberg.

The subtext of many of the recent tales—from Donald Trump’s massive cash-spending spree to Cohen’s $32 million flip of New York real estate—is that the atypical transactions are worthy of greater scrutiny. After all, why was the self-proclaimed “King of Debt” suddenly waist-deep in cash and on a spending spree in the midst of the global real estate crash? Where was Cohen’s money coming from—and where was it going?

It’s the old adage from the Watergate investigation: “Follow the money.”

The implication, particularly in the more fever-swampy portions of Twitter, is that there was money laundering afoot—probably Russian in origin. The “quid” perhaps, before the election and the “pro quo” afterward. But is that a real possibility—and if it was money laundering, by whom and how?

The payments appear to mirror suspicious activity that led to the earliest charges and investigative avenues of special counsel Robert Mueller’s probe, the money laundering and conspiracy charges leveled against former Trump campaign chair Paul Manafort and aide Rick Gates. (Gates has since pleaded guilty; Manafort’s case continues to move forward toward trial later this year.)

But to Treasury officials and law enforcement who have long pursued money laundering and terrorist financing probes, it’s not what Donald Trump or Michael Cohen did in any single transaction that raises red flags—it’s how they conducted business day in and day out. The layers of shell companies, the contracts involving pseudonyms, the law firm cut-outs to make deals.

"Many of the activities, when viewed in aggregate, point to a deliberate attempt to create opacity,” says Amit Sharma, who used to work on countering terrorist financing after 9/11 at the Treasury Department. “When you take two steps back, you see a murkiness and level of complexity with which the Cohen and Trump companies have operated—what are they hiding? Why are secondary and tertiary entities signing under pseudonyms and ‘cover' names? Truly legitimate, transparent companies don’t need to do that. Does this point to corruption and/or conspiracy? It certainly looks that way! Are all activities pointing to specific money laundering transactions? Not necessarily.”

The fundamental approach to Trump and Cohen’s empires should raise eyebrows—and evidently has with Mueller’s probe and prosecutors in the Southern District of New York—precisely because of the apparently great lengths they undertook to evade basic transparency. While not necessarily illegal—some of the tactics are, in fact, regular parts of complex businesses—the pattern of activity points to an attempt to evade one of the basic precepts of modern banking and anti-money-laundering efforts: Know your customer.

“What we call ‘covered institutions,’ that’s any financial institution overseen by US financial regulations, they have to have a comprehensive anti-money-laundering regime. It basically come down to one central question: Do you know your customer? Who’s behind the account, who has control over an entity or can facilitate transactions on its behalf, what are its sources of funds, and what is the normal, expected nature of its business or pattern of activity for that person or entity?" Sharma says. “Anytime a bank or financial institution spots activity that doesn’t match the regular pattern, they’re required to file suspicious activity reports with the Treasury Department.” (Those exact type of reports were triggered by odd withdrawals and payments by the Russian embassy around the time of the US election, and are the subject of part of Mueller’s probe, according to Buzzfeed.)