Jared Kushner testified on Thursday before the House select committee investigating the 6 January attack on the Capitol, becoming the first member of Donald Trump’s family to speak to investigators.

Democrat Elaine Luria, a member of the select committee, confirmed that Kushner appeared before the panel “voluntarily”, although she would not provide details on what he said.

“He was able to voluntarily provide information to us to verify, substantiate, provide his own take on this different reporting,” Luria told MSNBC. “So it was really valuable for us to have the opportunity to speak to him.”

Kushner appeared virtually before investigators and spoke to committee counsel, two sources told the Guardian. A spokesperson for the January 6 committee declined to comment about Kushner’s testimony.

Kushner is married to Trump’s eldest daughter, Ivanka Trump, and he served as a senior adviser to the former president. However, Kushner was not at the White House on 6 January as the Capitol attack unfolded because he was traveling back to Washington after a trip to Saudi Arabia.

One source said before Kushner’s interview that investigators planned to ask him about a text sent by Ginni Thomas, the conservative activist who is married to the supreme court justice Clarence Thomas, in the weeks after the election.

The Washington Post and CBS News reported last week that Thomas sent a text to Mark Meadows, Trump’s former chief of staff, on 13 November that seemed to reference Kushner. “Just forwarded to yr gmail an email I sent Jared this am. Sidney Powell & improved coordination now will help the cavalry come and Fraud exposed and America saved,” Thomas wrote.

Kushner may have also faced questions from the committee about Trump’s efforts to spread baseless claims of widespread fraud in the 2020 presidential election. According to Bob Woodward and Robert Costa’s book Peril, Kushner was involved in conversations about how to delicately tell Trump that he had lost the election to Joe Biden.

The White House said Biden would not assert executive privilege over the testimony of Kushner, allowing him to speak to the committee about conversations he may have had with Trump in the days and weeks before the Capitol attack.

“The president has spoken to the fact that January 6 was one of the darkest days in our country’s history and that we must have a full accounting of what happened to ensure that it never occurs again,” the White House communications director, Kate Bedingfield, said on Tuesday. “As a result, the White House has decided not to assert executive privilege over the testimony of Jared Kushner and Ivanka Trump.”

Asked whether Biden’s decision had been communicated to Kushner’s team, Bedingfield said: “I won’t speak to private communication between our attorneys and his.”

Ivanka Trump has said she is in talks to voluntarily appear before the committee, after the Guardian reported that the committee was considering issuing a subpoena to compel her to testify.

In a January letter to Trump, Thompson said the committee wanted to question her about what she witnessed in the Oval Office on 6 January. According to testimony from Keith Kellogg, the former national security adviser to Mike Pence, Trump witnessed a conversation during which her father pressured the vice-president to overturn the results of the election. Kellogg also testified that Trump made multiple attempts to convince her father to take action to quell the violence at the Capitol.

Thompson requested Trump’s “voluntary cooperation” with the committee, writing: “We respect your privacy, and our questions will be limited to issues relating to January 6th, the activities that contributed to or influenced events on January 6th, and your role in the White House during that period.”

Thompson initially proposed that Trump speak to the committee on 3 or 4 February, but those dates came and went without any progress. It remains unclear when Trump might testify or if she will provide any substantive information to the committee.

Hugo Lowell contributed to this report