A key congressional investigator will soon gain access to video of a deposition given by ex-British spy Christopher Steele, the author of the Trump dossier, in London this summer.

In a letter dated July 25, Senate Judiciary Chairman Chuck Grassley, R-Iowa, implored the lawyer for Aleksej Gubarev, a Russian entrepreneur who is suing BuzzFeed and Steele over the dossier, to hand over a transcript and video of the deposition.

That lawyer, Val Gurvits, told the Daily Caller that he will comply. “My client has instructed me from the very beginning of this lawsuit to fully cooperate with all U.S. government requests,” he said.

In his lawsuit brought on earlier this year, Gubarev claims his companies, Webzilla and XBT Holdings, were defamed by the publication of the dossier, which BuzzFeed published in full despite acknowledging that much of the information it contained could not be verified. The unverified dossier alleges that XBT used "botnets and porn traffic to transmit viruses, plant bugs, steal data and conduct 'altering operations' against the Democratic Party leadership" during the 2016 campaign.

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In January, Grassley, along with Sen. Lindsey Graham, R-S.C., a senior member of his committee, announced they had referred Steele to the Justice Department for a criminal investigation into false statements they believe he knowingly made to federal authorities about his communications with U.S. journalists.

Grassley's committee is examining the FBI's relationship with Steele, including how his dossier was used to convince a Foreign Intelligence Surveillance Act court to grant the authority to spy on onetime Trump campaign aide Carter Page.

Grassley said in his letter that it is his understanding that Steele has "refused all Congressional attempts to interview him."

The Senate Intelligence Committee has tried to arrange an interview, but as of July, Chairman Richard Burr, R-N.C., said "cooperation" issues had stymied that effort.