Professor Joseph Mifsud gained worldwide notoriety as the person who allegedly connected Trump's campaign with the Russians to destroy rival contestant Hillary Clinton and may have escaped the United States due to lies told by Papadopoulos.
Federal prosecutors with the special counsel's office had asked Judge Randolph Moss for a sentence of up to six months in prison.
The lies Mr. Papadopoulos told in his voluntary interview with the Federal Bureau of Investigation on January 27, 2017, prosecutors said, "undermined investigators' ability to challenge the professor or potentially detain or arrest him while he was still in the United States".
During his sentencing hearing Papadopoulos said his case should serve as a warning to others.
According to Bloomberg News, the committee indicated that an investigator had been used to find Mifsud, who had disappeared for months, and was told the Maltese professor may be dead.
"I do credit the sense that he does feel remorse", Moss said.
Papadopoulos's attorney, Thomas M. Breen, went further, saying "the President of the United States hindered this investigation more than George Papadopoulos ever could", by calling the investigation fake news and a witch hunt. He gave false statements about his contacts to the FBI, which the FBI said impeded their investigation into the extent that Russian meddling may have worked its way into the campaign.More news: UEFA Nations League Germany v France 06 September 2018
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Papadopoulos, a young oil and gas consultant, was the first Trump official to plead guilty and cooperate in the investigation into Russian interference in the 2016 US election. His client was also affected by Trump's cries of "fake news" and his casting of the Russian Federation investigation as a "witch hunt" just days before his FBI interview.
CNN's Tapper noted that Session's attorneys said that Sessions stands by his testimony, and denied encouraging a meeting with Russians.
Before the sentencing, Papadopolous made a statement, describing himself as a "patriotic American" who made a mistake by lying to investigators.
Trump named Papadopoulos as one of his campaign's foreign policy advisers on March 21, 2016, boasting to reporters: "He's an energy and oil consultant, excellent guy", a filing said.
He has testified that senior members of the Trump campaign encouraged him during 2016 to build ties with Russian Federation, including after he told them that Moscow possessed - and could be willing to share - dirt on Trump's election rival Hillary Clinton. While Trump has the legal power to, and has said he feels he has the full right sack the special counsel, the probe continues and Mueller is still at its helm.
Papadopoulos also made a similar claim about Sessions last week in court.
Papadopoulos's attorneys had asked for probation for their client and said in court filings that Papadopoulos misled investigators to try to save his professional ambitions and out of a "perhaps misguided loyalty to his master" but not for more sinister reasons. Last November, Mr Sessions testified to Congress that he had "pushed back" against Papadopoulos' offer.