George Nader was a key witness in Special Counsel Robert Mueller's Russia investigation.
Nader also informally advised President Donald Trump's team on foreign policy.
Now, CNN reports Nader was sentenced on Friday to 10 years in federal prison, stemming from his convictions on child sex charges.
The sentence draws a line under a disturbing case that exposed Nader's double life as a pedophile who also advised top US and Middle Eastern officials.
Earlier this year, Nader pleaded guilty to possessing child pornography, and admitted bringing an underage boy to the US for sex.
