At the time, it was one of the more controversial moments of Robert Mueller’s probe: Late last year, news broke that a federal agency turned over tens of thousands of private emails of Trump transition team officials to the special counsel’s team—without a warrant, and without getting the officials’ permission.

Now, according to communications reviewed by The Daily Beast, the transition team is fighting back. They are threatening to call for an inspector general’s investigation of the General Services Administration (GSA), which gave the emails to Mueller, and to potentially try to have officials there sanctioned by the D.C. Bar.

The transition team also charges that the GSA is trying to cover up the involvement of controversial FBI agent Peter Strzok in the allegedly illegal seizure of their emails. A lawyer for the transition team wrote that Strzok “played a larger-than-previously known role in unlawfully seizing our client’s records.”

The dispute is over communications that members of the transition team had over phones and laptops between Election Day and the inauguration. After the inauguration, those phones and laptops—and the communications made over them—were handed off to the GSA for safekeeping. According to the transition team communications reviewed by The Daily Beast, the GSA’s then-General Counsel Richard Beckler assured the transition team that it was merely housing the materials, and that any communications would be locked securely away from prying eyes.

“Mr. Beckler further acknowledged that, if a third party such as the special counsel’s office were to request copies of the PTT [Presidential Transition Team] emails, TFA [Trump for America] would and should be afforded an opportunity to identify and designate privileged materials that should not be reviewed by third parties,” the letter continued.

But that didn’t happen. Instead, when officials from Mueller’s special counsel probe asked the GSA for the materials, officials at the GSA acceded to their request, turning over tens of thousands of emails, as well as laptops and cellphones.

And, according to transition officials, the GSA didn’t tell the transition team about it.

The letter said the transition team only learned Mueller had their documents because they read newspaper stories describing confidential emails and pressed the GSA for an explanation.

After learning what had happened, the officials who helmed the transition team decided to try to get to the bottom of it. So they filed a Freedom of Information Act (FOIA) request with the GSA, demanding internal communications showing how their emails ended up in the special counsel’s hands without their permission.

The first batch of documents they received from the FOIA request was heavily redacted. But one name wasn’t blacked out: Peter Strzok, who Mueller fired after it was learned he had sent text messages to his paramour at the FBI ripping into Trump.

“God trump is a loathsome human.... omg he’s an idiot,” Strzok’s lover, Lisa Page, wrote to him in March of 2016, as Politico detailed.

“He’s awful,” Strzok replied.

In another message, Strzok suggested Trump presented a threat to the United States.

“I want to believe the path you threw out for consideration in Andy’s office—that there’s no way he gets elected—but I’m afraid we can’t take that risk,” he wrote a few months before Election Day. It is unclear who Andy is, though some believe him to be then-Deputy FBI Director Andrew McCabe.

When congressional investigators released Strzok’s texts, he quickly became a central foe for the right—including Trump. The president has tweeted multiple times about Strzok and Page, suggesting their correspondence proves the Mueller probe is just a politically motivated witch hunt. On Tuesday evening, he went after the pair.

“Wow, Strzok-Page, the incompetent & corrupt FBI lovers, have texts referring to a counter-intelligence operation into the Trump Campaign dating way back to December, 2015,” he tweeted. “SPYGATE is in full force! Is the Mainstream Media interested yet? Big stuff!”

Strzok’s political opposition to Trump also concerns the transition team. In the letter reviewed by The Daily Beast, Kory Langhofer—a lawyer for the transition team—wrote that Strzok’s name should be unredacted from documents returned in response to their FOIA request because there are “palpable reasons to believe that Mr. Strzok’s official actions may have been undergirded by his partisan proclivities.”

“[T]he repeated and widespread disclosure of Mr. Strzok’s participation in the special counsel’s investigation, compounded with the critical public interest in exposing potential government misconduct, easily vitiate whatever marginal privacy interests underlie the GSA’s withholdings and redactions,” Langhofer wrote.

In a separate letter, sent May 31, 2018, and also reviewed by The Daily Beast, transition team lawyers Langhofer, Thomas Basile, and Christopher Murray indicate the transition team is considering looking to have a senior GSA official reported to the inspector general and to the bar. At issue is whether Lennard Loewentritt, the GSA’s deputy general counsel, violated the trust of the transition team by releasing the emails to the special counsel. The GSA declined to comment for this story, but a GSA official told BuzzFeed News in December that the agency did not make any commitment to protect the transition team’s records. In the letter, the transition team says that claim is “categorically false.”

The transition team’s lawyers have also singled out the Mueller probe for criticism. In a letter sent to Mueller’s team on Jan. 12, 2018, and reviewed by The Daily Beast, the transition team lawyers accuse Mueller’s team of violating the Fourth Amendment of the Constitution by seizing the documents without a warrant. That letter also accuses Mueller’s team of abnegating its responsibility to protect the attorney-client privileged material it seized when it took the documents from the GSA, calling Mueller’s actions “surprising and troubling.”

“The trustees of TFA [the transition team] are actively contemplating the initiation of judicial proceedings to recover its unlawfully seized materials and/or the damages they continue to incur as a result of the breach and unwarranted seizure and improper search of its records,” the letter says in its conclusion.

That’s how lawyers say they’re thinking about suing. Ken Nahigian, the executive director of the transition team, said the possibility of taking legal action against Mueller’s team is still on the table.

“We have to explore every option in order to ensure that this issue is resolved for future transitions,” he said.