Michael Flynn will be a “principal witness” in the trial of his former business partner indicted for illegal foreign lobbying, according to court documents filed Friday.

In the filings, lawyers for Bijan Kian said that they needed to know exactly what the former U.S. national security adviser-turned-cooperating government witness told federal prosecutors.

Specifically, they want “all statements, transcripts, notes, records and memoranda” from federal prosecutors relating to anything Flynn told “any agent, employee, representative or elected official” of the US government.

Kian’s attorneys argue that the false statements Flynn made to Vice President Mike Pence and the FBI about his contacts with Russian officials, for example, damage his “credibility” as a witness.

The lawyers are also subpoenaing Covington and Burling, the D.C. law firm that worked with Flynn Intel Group, for a slew of documents and communications. They suggest that Covington attorneys violated attorney client privilege by divulging to the government, without Kian’s consent, information about the firm’s failure to register under the Foreign Agents Registration Act for its work for the Turkish government.

Kian is also sometimes referred to by his full last name, Rafekian.

“The documents requested from FIG’s outside counsel will allow the defense to develop at trial whether FIG’s outside counsel (i) gathered from Mr. Rafiekian information that he believed was privileged and (ii) used that otherwise privileged information that was obtained from one shareholder (Mr. Rafiekian) for the exclusive benefit of another shareholder (Mr. Flynn) in an admitted effort to reduce Flynn’s sentence in the case to which he has pled guilty in the District of Columbia,” the attorneys write.

Kian was indicted in December for allegedly acting as a foreign agent and conspiracy for his work on a project to discredit and extradite a U.S.-based Turkish cleric loathed by Turkey’s government. He pleaded not guilty.

Flynn entered into a plea agreement with special counsel Robert Mueller and other federal prosecutors in December 2017. He has admitted to lying to the FBI about his contact with Russian ambassador Sergey Kislyak and lying to federal prosecutors about the work he and Kian did at Flynn Intel Group.

Flynn is continuing to provide “substantial” assistance to various government investigations, according to Mueller’s team, and has not yet been sentenced.