Gee, how does the Treasury Dept. "collect a vast repository of records" in order to "piece money trails together and identify leads for criminal investigators", huh?
You don't suppose they ever wiretap anybody, do you?
Here:
U.S. Treasury Department agents have recently obtained information about offshore financial transactions involving President Donald Trump's former campaign chairman, Paul Manafort, as part of a federal anti-corruption probe into his work in Eastern Europe, The Associated Press has learned.
Information about Manafort's transactions was turned over earlier this year to U.S. agents working in the Treasury Department's Financial Crimes Enforcement Network by investigators in Cyprus at the U.S. agency's request, a person familiar with the case said, speaking on condition of anonymity because the person was not authorized to publicly discuss a criminal investigation. ...
Manafort, who was Trump's unpaid campaign chairman from March until August last year, has been a leading focus of the U.S. government's investigation into whether Trump associates coordinated with Moscow to meddle in the 2016 campaign. This week, the AP revealed his secret work for a Russian billionaire to advance the interests of Russian President Vladimir Putin a decade ago. ...
The Financial Crimes Enforcement Network, known as FinCEN, was established in 1990 and became a Treasury Department bureau soon after the Sept. 11, 2001, terror attacks. It collects a vast repository of records that financial institutions are required to report under the Bank Secrecy Act, such as suspicious activity reports and currency transaction reports, and assists law enforcement agencies in helping analyze complex data.
The agency is a part of an international network of so-called financial intelligence units that share information with each other in money laundering and terrorism financing investigations. Its work has been critical in helping officials piece money trails together and identify leads for criminal investigators.