 -- Trump campaign adviser Michael Caputo has been contacted by the House Intelligence Committee as part of the panel's investigation into Russian meddling in the 2016 presidential election, ABC News has confirmed.

The panel sent Caputo, a protege of longtime Trump political adviser Roger Stone, a letter on May 9 requesting his cooperation, and any documents and records pertinent to the investigation by May 22.

The committee also asked Caputo to preserve existing documents, and appear for a voluntary transcribed interview with staff, according to a copy of the letter obtained by ABC News.

Caputo, who officially worked for Trump's presidential campaign from November 2015 to June 2016, has repeatedly denied any contact with Russian officials or collusion during the campaign.

In his written response to the panel, he said he was never in contact with Russian officials or government employees during his time with the campaign.

The only time he ever discussed Russia with Trump was in 2013, "when he simply asked me in passing what it was like to live there in the context of a dinner conversation," Caputo wrote.

The focus on Caputo, first reported by The New York Times, comes as the federal investigation of Trump associates and potential collusion with Russian officials has turned to at least one Trump White House staffer, in addition to Trump campaign advisers.

Caputo was brought up in the committee's March 20 open hearing with NSA Director Mike Rogers and then-FBI director James Comey, when Rep. Jackie Speier, D-California, brought up his political consulting work in Russia.

Caputo lived in Russia in the 1990s, and briefly advised Gazprom Media, the media division of the Russian energy conglomerate with ties to Russian President Vladimir Putin.

House Intelligence Committee aides declined to comment.