WASHINGTON — A Russian businessman who helped arrange a meeting for Donald Trump Jr. to receive potentially damaging information about Hillary Clinton sent his own emissary to attend the June 2016 session at Trump Tower, according to his lawyer.

Scott S. Balber, a lawyer for Aras Agalarov, the businessman, said he sent an associate named Ike Kaveladze to the meeting, which took place during last year’s presidential campaign. Mr. Balber said that Mr. Kaveladze attended the meeting “just to make sure it happened and to serve as an interpreter if necessary.”

Besides the younger Mr. Trump and Mr. Kaveladze, the meeting was attended by a Russian lawyer, Natalia Veselnitskaya, and other officials from the Trump campaign.

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Mr. Balber said Ms. Veselnitskaya, who had worked with Mr. Agalarov on real estate deals in Russia, asked Mr. Agalarov to introduce her to Donald Trump Jr. as a favor.

President Trump and Mr. Agalarov worked together in 2013 when Mr. Trump brought the Miss Universe pageant to Moscow.

The names of the people who attended the June 2016 meeting first surfaced in an email sent by Rob Goldstone, a music producer and publicist working for Emin Agalarov, a Russian pop star who is Mr. Agalarov’s son.

“This is obviously very high-level and sensitive information but is part of Russia and its government’s support for Mr. Trump — helped along by Aras and Emin,” Mr. Goldstone wrote to Donald Trump Jr.

Mr. Kaveladze is Facebook friends with Mr. Goldstone and the younger Mr. Agalarov.

Mr. Balber said the Agalarovs have “no idea what Mr. Goldstone was thinking” when he wrote the email. “I would call it hyperbole or puffery,” he said. “It is absolutely not true.”

He described Mr. Kaveldaze as a longtime American citizen who speaks Russian fluently and nearly fluent English. “They had somebody show up at the meeting to make sure the favor was executed, that they carried through on it. And now they are in the middle of this tremendous storm,” he said.

The investigation into Russian meddling in last year’s election is being run by Robert S. Mueller, the former F.B.I director. Mr. Mueller’s team, made up of veteran F.B.I. agents and prosecutors, believes it has identified everyone who attended the meeting, according to one person familiar the investigation. Agents and prosecutors are eager to question everyone who was at the meeting, the person said.