WASHINGTON — The Senate Intelligence Committee has requested documents and testimony from Michael G. Flynn, the son of former national security adviser Michael Flynn, but has not received a response, three sources familiar with the matter told NBC News.
The committee, which is investigating possible collusion between the Trump campaign and Russia, is interested in Flynn’s work as his father’s aide and travel companion with Flynn Intel Group, the consulting firm retired Lt. Gen. Michael Flynn formed after he left government service, the sources said.
Sen. Richard Burr of North Carolina, the intelligence committee chairman, and Sen. Mark Warner, of Virginia the ranking Democrat, declined to comment when asked about the matter Monday by NBC News.
Michael G. Flynn’s lawyer, Barry Coburn, did not respond to a request for comment.
The younger Flynn, 34, accompanied his father on a 2015 trip to Moscow, where the elder Flynn sat next to Vladimir Putin at a dinner to celebrate Russia’s state-funded media network, RT. The younger Flynn can be seen in video from an associated event.
Ultimately, the committee could issue a subpoena to Flynn if he doesn’t comply, but he could assert his right against self-incrimination under the Fifth Amendment to the U.S. Constitution.
RELATED: Photos of Retired Army Lt. Gen. Michael Flynn
Retired Army Lt. Gen. Michael Flynn
Retired Army Lt. Gen. Michael Flynn
National security adviser General Michael Flynn delivers a statement daily briefing at the White House in Washington U.S., February 1, 2017. REUTERS/Carlos Barria
Retired Lt. Gen. Michael Flynn arrives at the Trump Tower for meetings with US President-elect Donald Trump, in New York on November 17, 2016.
(EDUARDO MUNOZ ALVAREZ/AFP/Getty Images)
Retired United States Army lieutenant general Michael T. Flynn introduces Republican Presidential nominee Donald J. Trump before he delivered a speech at The Union League of Philadelphia on September 7, 2016 in Philadelphia, Pennsylvania. Trump spoke about his plans to build up the military if elected. Recent national polls show the presidential race is tightening with two months until the election.
(Photo by Mark Makela/Getty Images)
Retired Lt. Gen. Michael Flynn, at podium, and Republican presidential candidate Donald Trump attend a campaign event with veterans at the Trump International Hotel on Pennsylvania Ave., NW, where Trump stated he believes President Obama was born in the United States, September 16, 2016.
(Photo By Tom Williams/CQ Roll Call)
WASHINGTON, DC - FEBRUARY 01: White House Press Secretary Sean Spicer (L) yields the briefing room podium to National Security Adviser Michael Flynn February 1, 2017 in Washington, DC. Flynn said the White House is 'officially putting Iran on notice' for a recent missile test and support for Houthi rebels in Yemen. (Photo by Win McNamee/Getty Images)
Army Lt. Gen. Michael Flynn, director of the Defense Intelligence Agency, prepares to testify at a Senate Armed Services Committee hearing in Dirksen Building titled 'Current and Future Worldwide Threats,' featuring testimony by he and James Clapper, Director of National Intelligence.
(Photo By Tom Williams/CQ Roll Call)
White House National Security Advisor Michael Flynn (C) arrives prior to a joint news conference between Canadian Prime Minister Justin Trudeau and U.S. President Donald Trump at the White House in Washington, U.S., February 13, 2017. REUTERS/Carlos Barria
U.S. National Security Advisor Michael Flynn boards Air Force One at West Palm Beach International airport in West Palm Beach, Florida U.S., February 12, 2017. REUTERS/Carlos Barria
National security adviser General Michael Flynn arrives to deliver a statement during the daily briefing at the White House in Washington U.S., February 1, 2017. Picture taken February 1, 2017. REUTERS/Carlos Barria
White House National Security Advisor Michael Flynn (L) arrives at Joint Base Andrews, Maryland, U.S., February 10, 2017. REUTERS/Carlos Barria
WASHINGTON, DC - FEBRUARY 10: (AFP OUT) White House National Security Advisor Michael Flynn (R) walks down the West Wing Colonnade following a bilateral meeting between U.S. President Donald Trump and Japanese Prime Minister Shinzo Abe February 10, 2017 in Washington, DC. Trump and Abe are expected to discuss many issues, including trade and security ties and will hold a joint press confrence later in the day. (Photo by Chip Somodevilla/Getty Images)
ATLANTA, GA - FEBRUARY 02: (L-R) SCAD Dramatic writing professor Chris Auer, Producer Sandra Leviton, Executive producer and writer Michael Flynn, Tv literary agent Jeff Greenberg and Literary manager and producer Kaila York speak on stage during the 'Inside the Writers Room' event on Day One of aTVfest 2017 presented by SCAD on February 2, 2017 in Atlanta, Georgia. (Photo by Vivien Killilea/Getty Images for SCAD)
Lieutenant General Michael Flynn (ret.), National Security Advisor Designate speaks during a conference on the transition of the US Presidency from Barack Obama to Donald Trump at the US Institute Of Peace in Washington DC, January 10, 2017. / AFP / CHRIS KLEPONIS (Photo credit should read CHRIS KLEPONIS/AFP/Getty Images)
Retired Lieutenant General Michael Flynn, U.S. national security advisor, attends a swearing in ceremony of White House senior staff in the East Room of the White House in Washington, D.C., U.S., on Sunday, Jan. 22, 2017. Trump today mocked protesters who gathered for large demonstrations across the U.S. and the world on Saturday to signal discontent with his leadership, but later offered a more conciliatory tone, saying he recognized such marches as a hallmark of our democracy. Photographer: Andrew Harrer/Bloomberg via Getty Images
WASHINGTON, DC - JANUARY 20: Michael Flynn walks out after a morning worship service on Inauguration day at St. John's Episcopal Church in Washington, DC on Friday, Jan. 20, 2017. (Photo by Jabin Botsford/The Washington Post via Getty Images)
WASHINGTON, DC - JANUARY 20: Attorney General nominee Sen. Jeff Sessions (R-AL) (R), talks with National Security Advisor Michael Flynn inside of the inaugural parade reviewing stand in front of the White House on January 20, 2017 in Washington, DC. Donald Trump was sworn in as the nation's 45th president today. (Photo by Mark Wilson/Getty Images)
Retired Lieutenant General Michael Flynn, White House national security adviser-designate, center, stands in an elevator at Trump Tower in New York, U.S., on Thursday, Jan. 12, 2017. Donald Trump is slated to meet with AT&T Inc.'s top executives on Thursday to discuss the company's proposed $85.4 billion bid for Time Warner Inc., according to people familiar with the matter. The president-elect has said he opposes the deal. Photographer: John Taggart/Bloomberg via Getty Images
WASHINGTON, DC - JANUARY 20: Donald Trump's National Security Adviser Gen. Michael T. Flynn (R) arrives on the West Front of the U.S. Capitol on January 20, 2017 in Washington, DC. In today's inauguration ceremony Donald J. Trump becomes the 45th president of the United States. (Photo by Drew Angerer/Getty Images)
Lieutenant General Michael Flynn (ret.) and National Security Advisor Designate and Ambassador Susan Rice, National Security Advisor during a ceremonial passing of authority while participating in a conference on the transition of the US Presidency from Barack Obama to Donald Trump at the US Institute Of Peace in Washington DC, January 10, 2017. / AFP / CHRIS KLEPONIS (Photo credit should read CHRIS KLEPONIS/AFP/Getty Images)
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NBC News reported last month that the younger Flynn is a subject of the criminal and counterintelligence investigation being conducted by Special Counsel Robert Mueller, who is also interested in Flynn’s work with his father’s consulting business.
Flynn responded on Twitter to the NBC News report, tweeting on Sept. 14: “I’m not the sub of any federal investigation.”
The elder Flynn was fired as Trump's national security adviser in February after it became public that he had misled Vice President Mike Pence about his conversations with the Russian ambassador in Washington.
A former business associate of Michael Flynn's said the younger Flynn played an important role in the day-to-day operations of Flynn Intel Group and served as his father's chief of staff.
Those responsibilities included attending meetings with his father and communicating with prospective clients, the former business associate said.