(CNN) House and Senate investigators are turning their attention to a Republican operative's hunt for Hillary Clinton's private emails from Russian hackers -- and his possible connections to senior members of the Trump campaign.

The operative, Peter W. Smith, was an Illinois-based Republican activist who during the presidential campaign sought to obtain emails he believed were likely stolen by Russian hackers from Clinton's private email server. He later was found dead in an apparent suicide weeks after telling a reporter about his efforts.

In a private interview earlier this month, a cybersecurity analyst Smith recruited for the effort reiterated to House investigators a comment that he had publicly made: He believed that Smith had ties to members of President Donald Trump's inner circle, including former national security adviser Michael Flynn , former chief strategist Steve Bannon and White House aide Kellyanne Conway — and may have been helping build opposition research for the Trump campaign, according to a source familiar with the matter.

Smith claimed connections to Flynn and senior Trump campaign aides in his effort to recruit cybersecurity experts to help him obtain and verify Clinton's emails, and now the House and Senate intelligence committees are probing whether those connections in fact existed.

The House panel has interviewed Matt Tait, the British security analyst who was recruited by Smith, and Jonathan Safron, a law student who worked as Smith's assistant. The Senate committee has reached out to Eric York, another security expert Smith enlisted in his email hunt, according to a source familiar with the matter.

GOP operative Peter Smith committed suicide at age 81 shortly after describing to the the Wall Street Journal his efforts online to track down Hillary Clinton's emails, which he believed had been hacked and stolen from her private server.

The strange case of Smith is one of many layers connected with Russia's meddling in the 2016 US election and possible collusion with Trump's associates, which are being scrutinized by both Congress and Justice Department special counsel Robert Mueller.

Smith spoke to The Wall Street Journal about his effort in May, saying he and the colleagues he enlisted found five groups of hackers claiming to have 33,000 deleted emails from the private server Clinton used during her tenure as secretary of state.

Two of the groups he determined were Russian, he said. "We knew the people who had these were probably around the Russian government," Smith told the Journal.

Smith said he was unable to verify the emails, and told all of the groups to give them to WikiLeaks.

Flynn's attorney, Robert Kelner, declined to comment. A person close to Bannon said the President's former chief strategist had never heard of Smith and was unaware of his efforts.

Conway acknowledged knowing about Smith from his work in Republican political circles, but told the Journal in July that she had no interactions with him during the campaign. She declined to respond to CNN's request for comment for this story. The White House referred questions to the Trump campaign, which did not respond to CNN request for comment.

Less than two weeks after he spoke with the Journal, Smith, 81, killed himself in a Minnesota hotel room. He left a suicide note in which he stated there was "no foul play," adding that his health had taken a turn for the worse and he had an expiring $5 million life insurance policy.

The House intelligence committee, which is running the chamber's Russia investigation, is talking to those who interacted with Smith during his quest for Clinton's emails, and the Senate panel appears to be taking similar steps.

"We're investigating all rational leads," said Rep. Mike Conaway, the Texas Republican who is leading the House Russia investigation, declining to comment further on the Smith matter.

A source familiar with the testimony told CNN Tait testified in a staff interview that he believed Smith was close to Flynn and his claims of a connection to Flynn and his onetime consulting firm, the Flynn Intel Group, were legitimate. Tait told the committee he believed Smith may have been working as an unofficial opposition research arm for the campaign, the source said.

The committee raised questions with Tait about how he knew of connections between Smith and the Trump campaign, the source said, and whether Smith's claims were credible.

Tait did not respond to requests for comment on his testimony. Safron confirmed he testified but declined to comment on the details. York declined to comment.

As part of his effort to recruit the British security analyst, Tait wrote that Smith gave him a document that claimed he had connections to Flynn, Bannon and Conway.

The document detailed a company Smith had set up for the endeavor "to avoid campaign reporting," Tait said. The document listed four groups involved, he wrote, including one entitled "Trump Campaign (in coordination to the extent permitted as an independent expenditure)," which listed Flynn, Bannon, Conway and other campaign officials.

"My perception then was that the inclusion of Trump campaign officials on this document was not merely a name-dropping exercise," Tait wrote. "This document was about establishing a company to conduct opposition research on behalf of the campaign, but operating at a distance so as to avoid campaign reporting. Indeed, the document says as much in black and white."

Tait said that the it wasn't initially clear how independent Smith was operating, but he said it was "immediately apparent that Smith was both well connected within the top echelons of the campaign and he seemed to know both Lt. Gen. Flynn and his son well."

Smith maintained a political blog that he regularly updated until his death. In several of the posts, he dismissed US government assessments about Russian election-meddling and openly embraced the Kremlin's favored narratives.

Clinton campaign chairman John Podesta's "emails were released through WikiLeaks, with no evidence of Russian involvement," Smith wrote shortly after the US intelligence community announced that Russian hackers stole Podesta's emails and relayed them to WikiLeaks for public release.

In addition to York, the Senate intelligence committee has asked for an interview and documents from conservative blogger Chuck Johnson, according to a July letter from the intelligence panel Johnson posted on his website. Johnson told Politico in July that he aided in Smith's effort to find Clinton's emails.

Johnson told CNN he has not provided any documents or spoken to the committee. He would not participate in a closed-door interview, he said, because he believes it's unconstitutional to force testimony in a closed setting. A Senate intelligence spokeswoman declined to comment.