A California man who says he served as a translator last year for Michael Cohen and a South Korean aerospace firm that paid Cohen’s company $150,000 said Tuesday that FBI agents recently interviewed him.

Mark Ko said in an email to The Washington Post that he spoke with the FBI about the arrangement “a few weeks ago.” Ko declined to provide details about investigators’ inquiries and said he was unsure whether the agents were part of the probe led by special counsel Robert S. Mueller III.

Ko’s statement is the first indication that federal authorities are examining Cohen’s contract with Korea Aerospace Industries (KAI) — one of several companies with substantial business before the U.S. government that hired Cohen, President Trump’s personal attorney and longtime legal fixer, after the 2016 election.