Special counsel Robert Mueller's office has obtained communications suggesting that a right-wing conspiracy theorist might have had advance knowledge that the emails of Hillary Clinton's campaign chairman had been stolen and handed to WikiLeaks, a source familiar with the investigation told NBC News.

Mueller's team has spent months investigating whether the conspiracy theorist Jerome Corsi knew WikiLeaks had obtained emails hacked by Russian intelligence officers before the public did and whether he passed information about the stolen emails to Trump associate Roger Stone, multiple sources said.

Mueller's investigators have reviewed messages to members of the Trump team in which Stone and Corsi seem to take credit for the release of Democratic emails, said a person with direct knowledge of the emails.

The source and other people familiar with the matter say they have seen no evidence suggesting either man played any role in the hacking or release of the emails. Stone has denied doing anything besides passing on information already in the public domain.

Corsi and his lawyer, David Gray, declined to comment. Mueller's spokesman, Peter Carr, said the office had no comment.

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