Special Counsel Robert Mueller‘s investigation has recently taken special interest in President Donald Trump’s inauguration after it was revealed that many influential Russians had also been in attendance. The big business owners attended several high profile, invitation-only events, traditionally reserved for top donors and close political allies, in the weeks leading up to the inauguration.

The guest list, obtained by ABC News, has become a point of interest for the Mueller probe. When looking into those invited, investigators came across several Russian guests with no clear diplomatic ties to the president.

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“It’s incredibly unusual,” said Stephen Kerrigan, former President of the 2013 Presidential Inaugural Committee. Having planned inaugural festivities for the last two elections, Kerrigan claims that typically every guest is scrutinized for foreign ties. “Particularly if they were going to be within arm’s reach of the President, they went through an intensive vetting process.”

Among those invited included Victor Vekselberg, a Kremlin-connected Russian oligarch and his cousin, Andrew Intrater. The two were some of the few invited to attend Trump’s inaugural Candlelight Dinner for their respective campaign donations of over $1 million. During the dinner, Vekselberg and Intrater were seated next to Trump’s current attorney, Michael Cohen. The following year, Intrater’s company, Columbus Nova, paid $500,000 to the same shell company Cohen used to funnel hush money to Stormy Daniels from January through August 2017. 

One oligarch was even ushered inside the Capitol for the traditional Inauguration Day luncheon hosted by the Joint Congressional Committee on Inaugural Ceremonies, according to a source familiar with the congressional investigations. The event is only privy to Congressional leadership and a few select guests of the president and vice president.