Congressional investigators are digging into a Republican operative’s efforts to obtain Hillary Clinton’s private emails from Russian hackers and his claims to be carrying out that hunt on behalf of members of the Trump campaign, CNN reported Monday.

The Senate and House Intelligence Committees are both reaching out to individuals recruited by the late Peter W. Smith, a veteran Chicago-based opposition research, for inside knowledge about how exactly his email hunt worked. Smith himself was found dead in an apparent suicide weeks after after the Wall Street Journal first reported on his email campaign.

Special counsel Robert Mueller’s team is also probing Smith’s work and whether, as he claimed, he was working “in coordination” with former National Security Adviser Michael Flynn or other high-level Trump campaign officials.

An anonymous source told CNN that British security analyst Matt Tait told the House committee that he believed Smith had close ties to Flynn, former chief White House strategist Steve Bannon and White House aide Kellyanne Conway. Tait went public with Smith’s efforts to recruit him in a June blog post for Lawfare, where he wrote that it was “apparent that Smith was both well connected within the top echelons of the campaign” and that he displayed a “reckless lack of interest in whether the emails came from a Russian cut-out.”

Indeed, Smith himself told the Journal that he “knew the people who had these were probably around the Russian government.”

The House panel has also interviewed Smith’s former assistant, law student Jonathan Safron, while Senate investigators have contacted Eric York, a separate security expert Smith reached out to for assistance in obtaining and verifying Clinton’s emails, according to CNN.

Conway and Bannon have previously denied any knowledge of this plot. Flynn’s attorney, Robert Kelner, declined CNN’s request for comment.

The Senate Intelligence Committee has also requested an interview and documents from far-right blogger Chuck Johnson, who told CNN he had done neither and would refuse any requests for a closed-door interview. Johnson recently joined pro-Russia congressman Rep. Dana Rohrabacher (R-CA) for a trip to meet with WikiLeaks founder Julian Assange, where they discussed their shared assessment that Russia played no role in providing Clinton campaign emails to Assange’s publication during the campaign.