A federal judge on Tuesday sentenced Dutch lawyer Alex van der Zwaan to 30 days in prison for lying to federal investigators, according to multiple reports, in the first criminal sentence to result from special counsel Robert Mueller’s investigation.

Van der Zwaan, who was also ordered to pay $20,000 in fines, pleaded guilty in late February to making “materially false, fictitious, and fraudulent statements and representations” to the special counsel’s office and FBI agents. 

According to the indictment, Van der Zwaan lied about his contacts with Trump campaign official Richard Gates and a Ukraine-based business associate of both Gates and former Trump campaign chairman Paul Manafort. He then tried to cover his tracks by deleting emails that the special counsel’s office had requested. 

Press reports have identified the businessman as Konstantin Kilimnik, a former Russian intelligence officer and a longtime associate of Gates and Manafort.