A review of the emails and documents — as well as interviews with people connected to the men — show that Mr. Cohen and Mr. Intrater were more closely linked than previously known. And the payments Columbus Nova made to Mr. Cohen, combined with Mr. Intrater’s donations to pro-Trump causes, help explain why their dealings have drawn the attention of Robert S. Mueller III, the special counsel examining Russian interference in the 2016 presidential election and the potential flow of foreign money into the campaign.
Mr. Mueller’s investigators have interviewed Mr. Intrater twice, focusing in part on his dealings with Mr. Cohen, according to a person briefed on the interviews. At a New York-area airport earlier this year, the investigators stopped Mr. Vekselberg and sought to question him. There is no indication that Mr. Intrater or Mr. Vekselberg are suspected of wrongdoing, or that their dealings with Mr. Cohen were improper.
“Columbus Nova has cooperated with all requests for documents and information from federal authorities,” said Richard Owens, a lawyer for Mr. Intrater and the firm.
In addition to the scrutiny from Mr. Mueller, federal prosecutors in Manhattan are investigating Mr. Cohen for possible bank fraud and election law violations, among other matters, according to people briefed on the inquiry. Federal agents raided Mr. Cohen’s hotel room, home and office last month, raising the prospect that his communications with Mr. Trump were in the hands of federal investigators, a cause for concern for the White House.
Lawyers for Mr. Cohen and Mr. Vekselberg did not respond to requests for comment.
Columbus Nova, like several other businesses that retained Mr. Cohen as a consultant, paid him through a shell company that Mr. Cohen had previously used to send $130,000 to Stephanie Clifford, a pornographic film actress who performs as Stormy Daniels, to keep her quiet about an alleged affair with Mr. Trump. (The president denies the affair.) Columbus Nova has said it had no idea that the shell company, Essential Consultants L.L.C., had been used for the payment to Ms. Clifford.
Some of the other companies that hired Mr. Cohen as a consultant, including AT&T and Novartis, have expressed regret over doing so since the arrangements came to light this month and spurred criticism for perceived influence peddling. Columbus Nova said it terminated its deal with Mr. Cohen by mutual agreement after it became clear that he was unable to devote the time necessary to recruit investors for the firm.