A businessman who served as a key witness in special counsel Robert Mueller's investigation now faces a charge of child sex trafficking in addition to transporting child pornography.

An indictment made public Friday in federal court in Alexandria, Va., charges Lebanese-American businessman George Nader, 60, with transporting a 14-year-old boy from Europe to Washington, D.C., in February 2000 and engaging in sex acts with him.

That charge comes on top of child pornography charges that had been levelled against him when he was arrested last month.

Nader's name shows up more than 100 times in Mueller's report. It details his efforts to serve as liaison between Kirill Dmitriev, a Russian banker close to Russian President Vladimir Putin, and members of President Donald Trump's transition team.

Nader also served as an adviser to the United Arab Emirates, a close Saudi ally, and in April 2017 wired $2.5 million US to a top Trump fundraiser, Elliott Broidy, through an opaque company in Canada — Xiemen Investments Limited — The Associated Press reported last year. The goal was to persuade the U.S. to take a hard line against Qatar, a longtime American ally but now an adversary of the U.A.E.

Nader's lawyers did not immediately return emails seeking comment.

While the sex trafficking indictment is new, the allegations that Nader engaged in sexual activity are not. Nader was convicted in the Czech Republic by Prague's Municipal Court of 10 cases of sexually abusing minors and sentenced to a one-year prison term in 2003.

Nader also pleaded guilty to a charge of transporting child-pornography images in Virginia in 1991.

The current investigation of Nader began last year when images depicting child pornography and bestiality were found on his phone after it was confiscated under a search warrant connected to the Mueller probe.

Nader is jailed as he awaits trial, which is set for Sept. 30.