Investigators working with special counsel Robert Mueller questioned Russian oligarch Viktor F. Vekselberg as part of the probe into Russian election interference, The New York Times reports. They stopped Vekselberg, a Russian billionaire who attended President Donald Trump’s inauguration, at a New York-area airport this year and wanted to search his electronic devices, according to the newspaper. It’s unclear what sparked Mueller’s interest in Vekselberg, who has many business ties to the U.S. He also attended a dinner in Russia in December 2015 that Michael T. Flynn, Trump’s former national security adviser, was present at. Vekselberg was one of seven Russia-linked oligarchs slapped with sanctions by the Trump administration in February.