Money laundering is a process that criminals use to disguise their illegal profits as legitimate capital.

It’s how they transform money made from drugs, illegal gambling, and human trafficking into dollars they can spend freely.

There are three main components: placement, layering, and integration.

Say you are a Russian oligarch. Maybe you’ve amassed a fortune through nefarious means. Maybe you can’t move your money into the U.S. because of sanctions.

First, you place your money into the financial system in ways that avoid suspicion from banks and law enforcement agencies.

Second, you shift, or layer, your money through numerous transactions to complicate the paper trail and confuse investigators — often using multiple wire transfers or shell companies.

Finally, you integrate your money back into the economy – after it’s been “cleaned” in such a way that it can’t be traced back to its criminal origins.

Read more: How to find money laundering vs. what House Intel Committee did

So how do Trump’s businesses fit in?

Buying real estate has long been a preferred method for criminals to launder money, especially Russian oligarchs and mobsters.

Real estate has fewer regulations than other businesses, it allows you to move large sums of money, and you can pay for it in cash or through shell companies to keep your identity hidden. You just need to find a property owner willing to turn a blind eye and not ask questions.

The Trump Organization has a reputation for looking the other way and readily accepting cash. In fact, some Trump properties are designated in such a way that you have to pay in cash.

Now that you have your property, it’s time to sell it. While the money you used to buy the real estate came from criminal activities, the money you received from the sale is clean, and the transaction is legitimate.

Read more: Money laundering in Trump SoHo

This matters. It’s more than just shady business practices. It’s illegal. And there have been documented cases of money laundering across numerous Trump properties:

  • Trump condo sales that show signs of money laundering total $1.5 billion.
  • In Panama, Trump convinced the investment bank Bear Stearns to issue a bond based on pre-sales of units, many of which were sold to Russian gangsters.
  • His Taj Mahal casino violated 106 anti-money laundering laws in its first year and a half of operation!

Rep. Adam Schiff (D-CA) has expressed concern over Trump’s connections to money laundering. “If the Russians were laundering money” through the Trump Organization, he said, “that would be a very powerful lever the Russians would have over the president of the United States.”

For his complicity in these financial crimes, or even his knowledge, Trump could be blackmailed. Or perhaps he already has been. His vulnerability begs the question: Who is he really working for?