Robert Mueller’s team is targeting Russian oligarchs in an effort to glean information about potentially illegal financial connections between Russian entities and the Trump campaign, CNN reported Wednesday. According to CNN, Mueller stopped at least two Russian oligarchs during their recent trips to the U.S., and in one of those instances searched the individual’s electronic devices upon arrival on a private jet in New York. A third wealthy Russian was also sent an informal request to volunteer documents and conduct an interview.

From CNN:

One area under scrutiny, sources say, is investments Russians made in companies or think tanks that have political action committees that donated to the campaign. Another theory Mueller’s office is pursuing, sources said, is whether wealthy Russians used straw donors – Americans with citizenship – as a vessel through which they could pump money into the campaign and inauguration fund.

Beyond the more explicit and brazen attempts at boosting the Trump campaign, such as the June 2016 Trump Tower meeting or Russian-linked social media accounts infecting the public discourse with inflammatory posts, another point of inquiry for Mueller is the more traditional means of support given to candidates: cash. Trump raised $333 million for his presidential campaign and an additional $106 million to put on his inauguration and Mueller appears to be plumbing the finances of certain Russians, particularly those with American citizenship, to see if they were used to pump foreign cash from Russia into the election. This has been a line of questioning Mueller’s investigators have been reported to be pursuing, as late last year “Mueller’s team asked some witnesses if they knew of Russians who made donations directly or indirectly to the Trump campaign,” sources told CNN.

• Russia Election Meddling