The Trump confidant was mentioned by Democrats pressing FBI Director James Comey and National Security Agency Director Mike Rogers over alleged links between the Trump campaign and the Russian government.
"On August 8th, Roger Stone, a longtime Trump political adviser and self-proclaimed political dirty trickster, boasts in a speech that he 'has communicated with (WikiLeaks founder Julian) Assange,' and that more documents would be coming, including an 'October surprise,'" said Rep. Adam Schiff, the ranking member of the House Intelligence Committee. "In the middle of August, he also communicates with the Russian cutout Guccifer 2.0, and authors a Breitbart piece denying Guccifer's links to Russian intelligence."
"Then, later in August, Stone does something truly remarkable, when he predicts that John Podesta's personal emails will soon be published. 'Trust me, it will soon be Podesta's time in the barrel. #Crooked Hillary,'" Schiff said, quoting an August 21 Stone tweet.
Schiff asked Comey if he was aware that Stone, a former aide of President Richard Nixon, played a role in the Trump campaign.
"I'm not going to talk about any particular person here today, Mr. Schiff," he replied.
The Democratic lawmaker asked Comey if he'd read press reports where Stone "proudly boasts of engaging in political dirty tricks
"I give you the same answer, sir," Comey replied.
Schiff also asked if the FBI director was aware of communications between Stone, Assange and his associates. Comey did not provide any details.
During the hearing, Stone tweeted that he hopes to testify before the intelligence committee to respond to the "smears" and "half truths" he claims have been launched against him.
"It's only fair that I have a chance to respond 2 any smears or half truths about alleged "Collusion with Russians" from 2day's Intel Hearing," Stone tweeted.
The hearing is designed to shed light on the state of FBI investigations into the extent of Russian meddling in the election campaign. Democrats are convinced that there is circumstantial evidence of wrongdoing in need of deeper investigation -- including with Stone.
"In terms of trying to understand this, I think of a spider web with a tarantula in the middle and the tarantula in my view is Vladmir Putin, who is entrapping many people to do his bidding and to engage with him and I would include those like Roger Stone," said California Rep. Jackie Speier.
Asked about Stone at a White House briefing Monday, press secretary Sean Spicer acknowledged that Trump has known him for a long time but didn't believe the two had spoken "any time recently."
The Senate Intelligence Committee previously asked Stone
, who has been connected to Trump for years, to preserve any records he might have that could be related to the panel's investigation into Russian actions targeting the US election, Stone confirmed to CNN recently.
Stone said his communication with "Guccifer 2.0
" -- the online persona who claims responsibility for hacking the Democratic National Committee -- was an innocuous "brief exchange" consisting of a few direct messages that amounted to nothing.
Any suggestion otherwise, he told CNN, is "a fabrication."
Stone also has previously told CNN he wants to testify before the committees as long as it is done publicly.
"I am anxious to rebut allegations that I had any improper or nefarious contact with any agent of the Russia state based on facts -- not misleading and salacious headlines," he said. "I am willing to appear voluntarily if the committee isn't looking for the headline of issuing a subpoena."