Alexandria, Virginia CNN  — 

George Nader, a key witness in the Russia investigation, pleaded guilty Monday to two sex crimes involving minors.

During an hour-long court hearing, Nader admitted that he brought an underage boy to the US for sex, and that he possessed child pornography depicting sexual abuse of toddlers.

Both of these crimes occurred years before Nader worked his way into President Donald Trump’s orbit after the 2016 election, when he served as an informal foreign policy adviser and attended high-level meetings.

Nader, 60, will be sentenced in April. He has been in jail since June, after a judge ruled that he was too dangerous to be released on bail, and wore a green jail uniform during the hearing in Monday. The child pornography charge carries a minimum sentence of 10 years in prison. Under the terms of a plea deal, the Justice Department agreed to recommend that Nader only receive that minimum 10-year term, though Nader’s sentence will ultimately be decided by federal Judge Leonie Brinkema.

A Middle East specialist with connections to powerful figures throughout the region, Nader became an informal foreign policy adviser to the Trump transition after the 2016 election. He attended meetings during the presidential transition with Trump’s son-in-law Jared Kushner, former chief strategist Steve Bannon and former national security adviser Michael Flynn.

These meetings later fell under the shadow of the Russia investigation, and Nader became an important cooperator for special counsel Robert Mueller’s investigation into Russian meddling. Nader provided information about contacts between the Trump transition and a senior Russian government official, and his testimony was ultimately cited dozens of times in the Mueller report.

He is cited extensively in the portions of the report about the Seychelles meeting between Trump supporter Erik Prince and a Russian banker with close ties to Russian President Vladimir Putin. His testimony about his role in the secret January 2017 liaison undercut Prince’s claims that the meeting was a random encounter and that it was not coordinated with anyone from the Trump transition.

In January 2018, FBI agents working for Mueller stopped Nader at Dulles International Airport outside of Washington, DC, to question him in the Russia probe. While examining his phones, the FBI agents found a dozen sexually explicit videos of underage boys, according to court records. That’s what led to his indictment last year on charges for transporting child pornography. Those charges were dismissed on Monday.

In previous court hearings, prosecutors have described Nader as a lifelong pedophile. He pleaded guilty in 1991 to transporting child pornography, and he was convicted in the Czech Republic in 2003 of sexual crimes that included hands-on contact with several underage boys. One of those victims appears to be the same underage boy that Nader brought to the US for “commercial sex” in 2000.

Separately, Nader was charged last year in a sweeping case involving illegal foreign donations to Democrat Hillary Clinton’s campaign in 2016. He pleaded not guilty to those charges, which alleged that Nader and others funneled money from a Middle East donor to Clinton. Nader has close ties to the leadership of the United Arab Emirates and worked as diplomatic middleman in the region for many years.