Over the last month, Special Counsel Robert Mueller's team has been diligently following up on leads regarding Roger Stone and whether he was in communication with WikiLeaks and its founder, Julian Assange, during the 2016 presidential election, several people familiar with the matter told The Washington Post on Sunday.

Stone, one of President Trump's longtime advisers, bragged during the campaign about his ability to get in touch with Assange, and he predicted future leaks from Assange's website. Now, prosecutors are looking at those comments, as well as private conversations he allegedly had with associates about his connection to Assange, to determine whether he knew in advance that WikiLeaks was going to publish emails hacked from Democrats, the Post reports.

In July, the special counsel filed charges laying out how Russian military intelligence officers created the online persona Guccifer 2.0 to spread the hacked emails through WikiLeaks, and used the Guccifer 2.0 Twitter account to exchange messages with Stone; Stone said those conversations were innocent.

Stone told the Post his only connection to WikiLeaks was through former friend Randy Credico, who had Assange on his radio show in 2016. A person familiar with the probe said Credico told Mueller's grand jury that in 2016, Stone told him he had a secret back channel to WikiLeaks. Mueller is also digging into Stone's relationship with Jerome Corsi, a conservative writer for a website centering around conspiracy theories, and whether he was the contact between Stone and WikiLeaks, the Post reports. Catherine Garcia