Pro Tip: Nothing is made better by bringing in the Internal Revenue Service.

Literally. Nothing.

That is what Robert Mueller is doing with the ongoing Russia probe, however.

A new report says Mueller is teaming up with the IRS’ Criminal Investigations unit.

The Daily Beast reported on Thursday that Mueller has teamed up with agents from the IRS’ unit dedicated to prosecuting financial crimes such as tax evasion and money laundering. One retired agent from the team said that the FBI doesn’t have the “expertise” that the CI has when it comes to investigating financial crimes.

“The FBI’s expertise is spread out over so many statutes—and particularly since 9/11, where they really focused on counterintelligence and counterterror—that they simply don’t have the financial investigative expertise that the CI agents have,” Martin Sheil told the Daily Beast. “When CI brings a case to a U.S. Attorney, it is done. It’s wrapped up with a ribbon and a bow. It’s just comprehensive.”

If true, this could be a very big clue as to which direction Mueller is taking the investigation.

This news comes on the heels of the news that Mueller was working with New York Attorney General Eric Schneiderman, in an investigation of Trump’s former campaign chairman, Paul Manafort.

Schneiderman and Mueller are reportedly investigating possible financial crimes, including money laundering, by Manafort in New York. Schneiderman has also been conducting his own state-level investigation of Manafort’s real estate dealings.

The further this thing goes, the further in hot water Manafort seems to be. How this blows back on Trump, if at all, remains to be seen.