But, given the email traffic suggesting the meeting was part of a Russian effort to help Trump’s candidacy, the presence at the meeting of a Russian-American with suspected intelligence ties is likely to be of interest to special counsel Robert Mueller and the House and Senate panels investigating the Russian election interference campaign.

As has been previously reported, the meeting was set up by music publicist Rob Goldstone, who told Donald Trump Jr. in an email chain that Veselnitskaya has "information that would incriminate Hillary and her dealings with Russia and would be very useful to your father."

Goldstone called Veselnitskaya a "Russian government attorney" — though she disputes that — and said the information was "part of Russia and its government's support for Mr. Trump.”

The Associated Press quoted Akhmetshin saying that Veselnitskaya brought with her to the meeting a plastic folder with printed-out documents that detailed what she believed was a flow of illicit funds to the Democratic National Committee.

The lobbyist said Veselnitskaya presented the contents of the documents to the Trump team, suggesting it could help the Trump campaign, he said.

“This could be a good issue to expose how the D.N.C. is accepting bad money,” The AP quoted Akhmetshin recalling her saying.

Veselnitskaya told a slightly different story in her interview with NBC News.

She said she brought with her a two-page document, one small part of which involved alleged D.N.C. funding issues. Most of it involved allegations against the Magnitsky sanctions, she said.

Donald Trump Jr., she said, asked if she had any further supporting documents.

“He clearly asked me if I had any financial records to back and support the idea that some funds from illegal sources went to DNC, went to Hilary Clinton," she told NBC News. “In reply to that, I told him that not only I don't have any financial records of that time — there was no chance that I could somehow, anyhow, have such records.”

She added that Trump Jr. ended the meeting by saying, “Well, the story that you've told us, it sounds very interesting but unfortunately at the moment, there is nothing that we, we can help you with about it. But maybe if we come to power, maybe one day, we will get back to you on that, because it really sounds interesting.”

Related: What's Next in the Trump-Russia Saga? Here's What We Know Now

Contacted by NBC News, representatives for Kushner and Manafort declined to comment.

On April 4, Sen. Charles Grassley, R-Iowa, chairman of the Judiciary Committee, wrote a letter to the Homeland Security department seeking information about Akhmetshin, saying that Akhmetshin admitted to having a background in Soviet counterintelligence. He reportedly served as a sergeant, a non-commissioned role in the Soviet military.

Grassley said Akhmetshin had failed to register as a foreign agent even though he had been lobbying in the U.S. for Russian interests. Grassley also charged that Akhmetshin had been working with Fusion GPS, an opposition-research firm that had compiled a highly disputed dossier on Donald Trump.

Fusion GPS has also worked on the campaign to raise questions about the story behind the Magnitsky Act.

Alan Futerfas, the attorney retained by Donald Trump Jr., told NBC News two other people accompanied Veselnitskaya to the meeting — someone Futerfas described as a translator and someone he described as a "friend of Emin [Agalarov]’s and maybe as a friend of Natalia [Veselnitskaya]’s.”

Futerfas said he has talked with that individual. "He is a U.S. citizen. He told me specifically he was not working for the Russian government, and in fact laughed when I asked him that question.”

It was not clear whether Futerfas was referring to Akhmetshin.

Agalarov is a pop star and a client of Rob Goldstone, a music publicist who arranged the meeting with Trump Jr. Agalarov appeared in a music video with Trump when the Miss Universe pageant, which Trump owned at the time, was held in Moscow in 2013.

Futerfas confirmed that, “for the purpose of security or otherwise, the names were reviewed” but said Trump Jr. knew nothing about the man's background at the time of the meeting.

When asked about whether he had concerns, knowing what he knows now, Futerfas responded: “I have absolutely no concerns about what was said in that meeting.”

Veselnitskaya, in an exclusive interview with NBC News, denied having any connection to the Kremlin and insisted the meeting was to discuss sanctions, not the presidential campaign.