George Nader, a man who served as a key witness in special counsel Robert Mueller’s probe into Russian interference in the 2016 presidential election, faces new charges of child pornography, sex trafficking and obscenity.

He has pleaded not guilty, according to The Washington Post. The trial is slated for September and Judge Leonie M. Brinkema of the U.S. District Court for the Eastern District of Virginia did not allow him to leave on bail, citing “the nature of the charges and [his] extensive overseas connections,” the Post reported Friday.

According to The Daily Beast, which first reported Nader’s new indictment ahead of its unsealing, the new charges stem from Nader allegedly having sex with a 14-year-old boy he transported from Europe.

He already faces charges of transportation with child pornography for allegedly traveling with illegal material on his phone in 2018. He was arrested last month upon returning to the U.S. and remains in custody in Virginia.

Nader, an informal adviser to the United Arab Emirates’ crown prince, had ties to several of President Donald Trump’s aides. Nader appears multiple times in the Mueller report, which said he served as a liaison for high-level officials in the Middle East and Russia trying to connect with the Trump campaign.

Nader has faced charges of transportation with child pornography before. He pleaded guilty in 1991 and served six months in prison.