The presence of prominent Russian business leaders and activists at Inauguration Day 2017 drew the attention of the FBI.

Counterintelligence officials at the FBI were interested in about half-dozen Russians at the event, but it is unclear which of the attendees were of concern.

A ccording to the Washington Post, Viktor Vekselberg, a businessman who is friendly with Russian President Vladimir Putin, Boris Titov, a politician running for president of Russia and Natalia Veselnitskaya, the lawyer who attended the now-infamous June 2016 meeting with Donald Trump Jr. at Trump Tower were all in attendance.

Veselnitskaya also later attended a black-tie inaugural party hosted by the campaign committee of Rep. Dana Rohrabacher, R-Calif., an associate who traveled with her revealed to the Post.

Special counsel Robert Mueller is leading a criminal investigation into Russia's election meddling in the 2016 election and possible collusion with the Trump campaign. The probe thus far has led to two indictments and two guilty pleas.

Multiple congressional committees are also conducting separate investigations into Russian interference.