Lawyers representing the firm that put together the so-called Trump dossier wrote a scathing letter to House Intel Chairman Devin Nunes (R-CA) — who has recused himself from the committee’s Russia probe, but nonetheless issued subpoenas to the firm — accusing Nunes and his staff of operating with a “pattern of unprofessional conduct.”

“Now that you, and by extension, your staff, have proven to be unreliable partners in good faith negotiations, we cannot reasonably be expected to trust anything that you or your staff would represent to us,” the lawyers for Fusion GPS said Monday in the letter. “We cannot in good conscience do anything but advise our clients to stand on their constitutional privileges, the attorney work product doctrine and contractual obligations.”

The lawyers signaled that Fusion GPS would not be turning over the documents Nunes’ subpoena requested (though the firm did preserve them). The lawyers said that, if compelled to appear in front of the committee, Fusion GPS representatives would invoke their constitutional privileges not to testify. They laid out a number of reasons they believed Nunes and his staff had acted in “bad faith” in issuing the subpoenas, including him doing so unilaterally despite his recusal as well as various “infirmities” in the subpoenas themselves.

The dossier and the private investigators who put it together have become of interest to the various entities investigating Russian meddling in the 2016 election. Fusion GPS co-founder Glenn Simpson was interviewed for 10 hours by the Senate Judiciary Committee and Special Counsel Robert Mueller’s team has reportedly met with the dossier’s author Christopher Steele, a former British spy.

In their letter Monday, Fusion GPS’ lawyers said the firm had been working with committee staff on finding a “path toward voluntary cooperation,” until Nunes surprised them with a set of subpoenas issued Oct. 4 for documents and testimony in the coming weeks.

“Despite your recusal from the Committee’s Russia investigation after falling under scrutiny by the House Ethics Committee, your unilateral issuance of these subpoenas violates your recusal and further undermines the legitimacy of this investigation,” the letter said.

According to the Fusion GPS letter, the subpoenas appear to have included instructions for the CIA instead of for Fusion GPS — a product, the lawyers said, of Nunes’ “haste to circumvent your own Committee’s investigation, rules, process and Ranking Member.”

The lawyers also accused Nunes’ staff of leaving off committee rules normally attached to subpoenas “either out of malice or as a consequence of your haste to circumvent the Committee’s process and its Ranking Members.”

The lawyers went on to suggest that Nunes’ actions could have a chilling effect on organizations like Fusion GPS that engage in political research.

“The subpoenas here seek to expose the confidential internal records of an organization involved in political activity merely to harass a group whose work you as Chairman want to discredit for political reasons,” they said.

A spokesman for Nunes did not respond to TPM’s request for comment.

In April, Nunes announced he was recusing himself from House Intel’s Russia probe, after scrutiny of his decision to brief President Trump on information he’d received on alleged Obama administration “unmasking” without first checking in with the rest of the committee.

He has continued, however, to insert himself in Russia-related matters, including in his interaction with the dossier firm as well as his threats to hold Justice Department officials in contempt over their refusal to turn over dossier-related documents.

Read the full letter to Nunes below: