President Donald Trump is careening towards a face-off with special counsel Robert Mueller.

The President and his legal team are going on the offensive after reports this week indicated that Mueller’s investigation into Russia’s interference in the 2016 election is digging into the President’s business transactions with Russian associates. Trump told the New York Times that he would see any review of his and his family’s finances unrelated to Russia as a “violation” of the probe’s parameters.

In just the past 24 hours, the Times and Washington Post have reported that Trump is taking extraordinary steps to discredit Mueller’s investigation, including digging through his teams’ campaign donations and past clients. The President has also asked about his power to pardon his aides, family, and himself, according to the Post, as if to preempt whatever Mueller’s team may find.

Jay Sekulow, who has assumed a larger role in the President’s reshuffled outside legal team, told the Post that reports that Mueller is investigating a number of Russia-related transactions Trump carried out in the last decade or so date too far back, and are thus “far outside the scope of a legitimate investigation.”

Unfortunately for the President, legal experts and former DOJ officials say, this is just how large-scale government investigations work.

“The problem is you don’t really know what is Russian,” Nick Akerman, a former federal prosecutor who worked on the Watergate investigation, told TPM. “A lot of stuff could be hidden in companies and under names of other people, you just don’t know. You’ve got to look at everything to determine what really relates to the Russia connection here.”

“It’s not up to him as to what the scope of this probe is, that’s for sure,” Akerman added, saying investigators are “not going to ignore stuff that is criminal.”

Financial transactions are well within the wide purview Deputy Attorney General Rod Rosenstein laid out in his May memo appointing Mueller as special counsel, as legal observers have noted.

Susan Hennessey, a former attorney at the National Security Agency’s Office of General Counsel and managing editor of the Lawfare blog, wrote on Twitter that the “Trump family finances are absolutely, 100% fair game.”

“The financial arrangements or dealings, those could be related to why there was collusion or incentive or motive to collude,” Tracy Schmaler, a former Justice Department spokesperson during President Obama’s first term, told TPM. “So I wouldn’t say it’s out of bounds so much as filling in the picture.”

“The relationship with Russia and Russian officials predates his run for the presidency,” Schmaler added.

Rosenstein’s memo granted Mueller sweeping authority to look into any links between the Trump campaign and Russia; “any matters that arose or may arise directly from the investigation”; and any matters within the scope of federal regulation 600.4(a), which includes obstruction of justice and other matters pertaining to efforts to derail the special counsel probe.

Although Trump told the Times that he is “not under investigation” and “didn’t do anything wrong,” the Washington Post previously reported that Mueller’s team had taken control of a federal investigation into whether the President obstructed justice by abruptly firing James Comey as FBI director because of the “Russia thing,” as Trump put it.

And as Comey testified before Congress in June, it’s possible that in the course of its work the special counsel could uncover crimes unrelated to Russia’s interference in the U.S. election or the Trump campaign’s potential coordination with those efforts.

“In any complex investigation, when you start turning over rocks, sometimes you find things that are unrelated to the primary investigation, that are criminal in nature,” Comey told the Senate Intelligence Committee.

Mueller’s powerhouse team of more than a dozen attorneys has experience in national security, fraud, money-laundering, organized crime, espionage, cybercrime and public corruption, offering an indication of just how wide-ranging the investigation may be.

A previous federal probe centered around a president’s private dealings took a winding path of a different sort. Independent prosecutor Kenneth Starr was appointed in 1994 to investigate a decades-old failed Arkansas real estate involving Bill and Hillary Clinton; the impeachment report he filed four years later focused instead on Bill Clinton’s affair with White House intern Monica Lewinsky.

All that special counsel investigators are required to do is follow the threads presented to them, wherever they might lead, as Senate Intelligence Committee chairman Richard Burr (R-NC) affirmed Thursday to CNN. Any topic related to Russia, Trump and his campaign associates is fair game.

“If they were investigating Donald Trump when he was five years old and ran a lemonade stand in Queens, I’d say, yeah, that’s probably beyond the scope,” Akerman, the former Watergate prosecutor said. “But if it turns out that the lemonade stand was done a year ago and was in Moscow and related to the same characters who showed up at the meeting with his son [Donald Trump Jr.], well I might feel a little differently about it.”

The looming, unanswered question, then, is whether a President who has fired his FBI director, scorned an attorney general who was his campaign’s most loyal supporter, and offered a national newspaper his view on the acceptable scope of a sprawling federal investigation that now touches on his own business dealings would go as far as to fire the man leading it—again.

Republican lawmakers have scoffed that there’s no chance, but his legal team is spreading the news that he’s already laying the groundwork to do so.

This post has been updated.