Lev Parnas, a former Rudy Giuliani associate charged with financial crimes, is looking to share more material with congressional investigators, according to a letter his lawyer has sent to a federal judge. The letter, filed in court on Monday evening, indicates that the committee first tasked with helming the impeachment inquiry is gathering additional evidence about Trump World

In the letter, Parnas’ lawyer Joseph Bondy said the Justice Department will share materials with his client on Tuesday that it seized from his home and at his arrest. The materials include documents and the contents of an iPhone. Bondy then asked Judge Paul Oetken of the Southern District of New York to allow him to share those materials with the House Intelligence Committee; a court order currently bars him from sharing them with anyone. The Justice Department has said it does not object to him giving the material to Congress. 

“Review of these materials is essential to the Committee’s ability to corroborate the strength of Mr. Parnas’s potential testimony,” Bondy wrote. 

The potential new document dump comes as House Speaker Nancy Pelosi deliberates on when to send the House’s articles of impeachment to the Senate. The House voted largely along party lines to pass two articles of impeachment on President Donald Trump earlier this month. The next step, which Pelosi has not yet taken, is to send the articles to the upper chamber for trial.

Trump’s relationship with Ukraine—in particular through his intermediary and personal lawyer Giuliani—is at the center of the impeachment process. Parnas had a front-row seat to much of Giuliani’s Ukraine-related activity. 

Federal authorities arrested Parnas and his associate Igor Fruman at Dulles Airport in October and charged them with conspiring to illegally funnel money from a foreign national into an American election. For many months before their arrest, the two worked with Giuliani to investigate allegations about former Vice President Joe Biden’s son Hunter, who served for a time on the board of a scandal-dogged Ukrainian energy company. At the same time, the trio pushed for the ouster of U.S. Ambassador to Ukraine Marie Yovanovitch from her post as the top U.S. diplomat in Kyiv. Their efforts succeeded, and Trump removed her from the job in May.

Two months after removing Yovanovitch, Trump had the now-infamous phone call with Ukrainian President Volodymyr Zelensky in which he asked the newly elected leader to work with Giuliani to scrutinize the Biden-linked company, as well as allegations about Ukrainian meddling in the 2016 election. Trump’s former top Russia official, Fiona Hill, said the Kremlin is pushing those allegations as part of a disinformation campaign designed to harm Ukraine. 

Parnas and Fruman, both Soviet-born U.S. citizens, made hefty political contributions through an entity they started called Global Energy Partners. And they built connections on Capitol Hill; after then-Rep. Pete Sessions sent a letter to Secretary of State Mike Pompeo calling for Yovanovitch’s removal, a PAC the pair supported shelled out a huge sum to boost his re-election bid. Sessions’ name was also batted around within the Trump administration as a potential replacement for Yovanovitch, though any efforts to install him there didn’t get traction. 

Parnas and Fruman have both pleaded not guilty. And Parnas indicated he would cooperate with the congressional impeachment inquiry. Because of his close proximity to Giuliani, he may have significant visibility into Giuliani’s actions that other witnesses lack. For instance, a senior Zelensky aide confirmed to The Daily Beast that Parnas was present for a meeting he had with Giuliani where they discussed the U.S.-Ukraine relationship. 

Parnas’ lawyer also said the Floridian worked to help Rep. Devin Nunes’ team with its investigative work. Phone records released later by impeachment investigators indicated there was communication between Parnas and Nunes himself, though Nunes has said he doesn’t remember talking with the Giuliani pal.