CNN reported last week that the individual was there on behalf of a Russian family, the Agalarovs, who had asked for the meeting to be set up, according to two sources familiar with the circumstances.
, which took place in Trump Tower in New York City, involved Donald Trump Jr., Trump son-in-law Jared Kushner, then-campaign manager Paul Manafort, Russian lawyer Natalia Veselnitskaya, publicist Rob Goldstone, Russian-American lobbyist Rinat Akhmetshin and at least two other people, sources familiar with the meeting have told CNN.
The meeting has drawn widespread scrutiny since The New York Times reported on it earlier this month.
In the wake of the Times' reporting, Trump Jr. posted a series of emails on Twitter between himself and Goldstone, a publicist for Emin Agalarov -- a Russian-Azerbaijani pop star who has previously done business with the Trumps alongside his father Aras Agalarov, a Russian real estate mogul with ties to Russian President Vladimir Putin.
In the emails, Goldstone pointed to the Russian attorney as the source of potentially damaging information on Hillary Clinton as "part of Russia and its government's support for Mr. Trump."
Futerfas says the person, who he declined to name, was a US citizen and said he was not employed by the Russian government. But Futerfas acknowledged he didn't know his entire history. The Agalarovs and their attorney have not publicly explained who the employee was who attended.
Futerfas says during his conversation the Agalarov representative corroborated what has already been reported about the meeting: that in the first couple of minutes there were pleasantries exchanged and then the Russian lawyer discussed the information she allegedly had about Russia donating to the Democratic National Committee and Hillary Clinton before moving on to the topic of adoptions.
Futerfas says he has never spoken to Rinat Akhmetshin.
He also says no one to whom he has spoken, including his client, Trump Jr., has any recollection of the document that the Russian lawyer is reported to have left behind in the meeting. Futerfas said it is possible that the participants don't remember.
As for whether Trump Jr. will voluntarily testify in response to a request from the Senate Judiciary Committee, Futerfas would only say, "We are in discussions with the various committees."
He also defended Trump Jr. as being willing to tell the full story even before the initial New York Times article appeared.
"Don Jr. and his counsel were fully prepared and absolutely prepared to publish or make a statement that was a fulsome statement about the nature of the meeting, what led to the meeting, what the conversation was in the meeting"
Futerfas also confirmed that the $50,000 that the Trump re-election campaign paid in June to his firm was, at least in part, for work he's now doing for Donald Trump Jr.