The former Trump campaign adviser who accepted a plea deal for lying to the FBI about his contacts with Russians is a “proactive cooperator” with federal investigators, according to court documents unveiled on Monday.

The term, which refers to George Papadopoulos, generated speculation that the 30-year-old energy consultant has worn a wire to help prosecutors in the Office of Special Counsel Robert Mueller, who is investigating Russian interference in the presidential campaign.

The reference to Papadopoulos’ status is found in a court filing submitted by prosecutors asking a federal judge to seal court filings in the case on the basis that “premature disclosure” of his arrest “would significantly undermine his ability to serve as a proactive cooperator.”

The website Hot Air explored the meaning of the term, and pointed to a 2001 federal court case which explained that “proactive cooperation is generally understood to mean that the defendant will engage in some type of undercover work on behalf of the Government, such as wearing a wire and/or meeting face to face with persons suspected of involvement in criminal activity.”

At a plea hearing held on Oct. 5, Aaron Zelinsky, a prosecutor in the Office of the Special Counsel, shed light on Papadopoulos’ cooperation. Zelinsky said that at Papadopoulos’ sentencing, prosecutors would make note of his “efforts to cooperate with the Government” as long as he continued “to meet with and provide information to the Government on request.”

Papadopoulos was arrested on July 27 on charges that he lied to FBI agents during a Jan. 27 interview. Agents met with Papadopoulos as part of the bureau’s investigation into possible collusion between the Trump campaign and Russian government.

As part of his plea deal, Papadopoulos acknowledged that he lied to agents during that meeting about his interactions with three Russian nationals. Papadopoulos initially claimed that he knew the Russians prior to joining the Trump campaign on March 6, 2016. But investigators obtained Papadopoulos’ emails and social media exchanges, which showed that he was lying.

Papadopoulos discussed arranging meetings between Russian government officials and the Trump campaign. One of Papadopoulos’ contacts, a London-based professor, also told him in April that the Russian government had obtained “thousands” of Hillary Clinton’s emails.

The White House on Monday downplayed the revelations, saying that Papadopoulos played a small part on the campaign and that the Trump team did not collude with the Russian government.

Papadopoulos’ Oct. 5 plea deal and his earlier arrest remained a closely held secret until Monday, just hours after Mueller’s office unsealed an indictment against former Trump campaign chairman Paul Manafort and his business associate, Rick Gates.

Manafort and Gates are charged with money laundering and conspiracy. The indictment provides no evidence of collusion between the Trump campaign and Russian government.

The revelation that Papadopoulos was serving as a “proactive cooperator” touched off widespread speculation about how much he had done to help the Mueller team.

Ron Hosko, a former assistant director of the FBI’s criminal division, says that it is possible that Papadopoulos wore a wire as part of his cooperation agreement.

“I think it’s a fair assessment that it means Mueller and Co. might have been working with [Papadopoulos] to engage other subjects in conversation along the lines suggested in the article,” said Hosko, referring to the Hot Air article which discussed the possibility of Papadopoulos wearing a wire.

Recordings of Papadopoulos’ conversations could have then been used to approach additional subjects.

On CNN, legal analyst Jeffrey Toobin said that the government’s disclosure strongly suggests that Papadopoulos was wearing a wire or recording conversations with Trump associates.

“What this says to me is that Papadopoulos between July and October was wearing a wire. He was recording conversations secretly with people who are subjects and targets of this investigation,” he said, adding that “that’s the only reasonable explanation of what’s in those court papers.”

“If he was wearing a wire, this summer and fall, think about that, just weeks ago, that is a whole new chapter of possibilities in this investigation and potentially a very, very big deal.”

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