George Nader, a key witness in former special counsel Robert Mueller’s Russia investigation, pleaded guilty to bringing a teenage boy to the United States for sex and possessing child pornography.

Nader, 60, faces 10 to 30 years in prison as part of the plea agreement, according to reports.

Search warrants unsealed last year revealed the FBI found child pornography in Nader’s possession during the Russia investigation. The warrants alleged at least a dozen videos containing child pornography were found on his phones, some involving animals and boys as young as 2 years old.

Nader was also accused of taking a 14-year-old boy from the Czech Republic to his Washington, D.C., home in 2000 and using him for sex. Two years later, Czech authorities arrested Nader amid allegations that he had sex with underage boys in the Czech Republic between 1999 and 2002. He was convicted in May 2003 of molesting children, according to the search warrants.

[Read: Convicted sex offender and Mueller witness George Nader indicted for illegal contributions to boost Hillary Clinton]

When law enforcement in the U.S. learned of the 14-year-old boy in 2002, Nader had left the country.

Nader also pleaded guilty to a federal pornography charge in 1991 and was sentenced to six months in prison after he was found with two reels of videotape hidden in candy tins when he arrived at the Washington-Dulles International Airport.

The Lebanese-American businessman met with officials and associates of President Trump’s circle and Russian and Middle Eastern officials in 2016 and 2017. He helped set up a January 2017 meeting in the Seychelles between Trump associate and Blackwater founder Erik Prince and a Russian official with close ties to Russian President Vladimir Putin.

Nader was mentioned more than 100 times in Mueller’s 448-page report on the Russia investigation. He was interviewed by the FBI on Jan. 19, 2018; Jan. 22, 2018; and Jan. 23, 2018.

The FBI did not discover until nearly a month after his interviews that his devices contained child pornography. He was charged in April 2018 but wasn’t arrested until June 2019, upon his return to the U.S.