A search warrant application unsealed on Wednesday revealed closer links than previously known between President Donald Trump’s former campaign manager Paul Manafort and a Russian oligarch with close ties to the Kremlin.

In an affidavit attached to the July 2017 application, an FBI agent said he had reviewed tax returns for a company controlled by Manafort and his wife that showed a $10 million loan from a Russian lender identified as Oleg Deripaska.

The application to search Manafort’s Virginia apartment was granted, providing key evidence for Special Counsel Robert Mueller’s indictments of Manafort as part of his investigation into Russia’s alleged meddling in the 2016 presidential campaign.

Mueller has been investigating the financial links between Manafort and Deripaska, a metals magnate who is known to be close to Russian President Vladimir Putin. Deripaska was among the Russian oligarchs sanctioned by the United States in April.

Mueller also has indicted Konstantin Kilimnik, a political operative who sometimes served as an intermediary between Manafort and Deripaska. In court filings Mueller’s prosecutors have said Kilimnik has ties to Russian spy agencies, which Kilimnik denies.