After Person 2 was subpoenaed to the House committee, Stone invoked the name of Frank Pantangeli, a fictional mobster in the movie “Godfather Part II’’ who developed memory problems as he testified before Congress.

A self-described political showman and dirty trickster whose career dates to the Nixon administration and who famously has a Richard Nixon tattoo on his back, Stone was a Trump campaign aide until his abrupt departure in August 2015, but he remained an informal adviser.

Stone has given varying accounts about whether he had advance knowledge that WikiLeaks would post a cache of private emails stolen from the Democratic National Committee, some of which embarrassed Democratic leaders and led to the resignation of the party chairwoman in the final weeks of the 2016 presidential campaign.

Twitter Messages

Even so, he has acknowledged exchanging private Twitter messages with an account claiming to be Guccifer 2.0, a hacker persona linked to the Russian government. A U.S. indictment of 12 Russian hackers thought to be responsible for the DNC email theft referred to an unnamed American close to senior members of the Trump campaign who was in contact with the hackers. Stone told CNN just after the July indictment that he was “probably” that person.

Before the emails were made public in October of 2016, Stone gave a speech and posted a series of tweets that seemed to foreshadow their disclosure and acknowledge that he served as a “backchannel to Assange,” referring to WikiLeaks founder Julian Assange, who has been in the Ecuadorian Embassy in London since 2012 because of his concerns that he would be arrested if he left the building.

Since then, Stone has denied any prior knowledge of the stolen emails. U.S. prosecutors and intelligence agencies say that hackers commissioned by the Russian government were responsible for the theft.

CNBC, citing unnamed people familiar with the matter, reported on May 3 that Mueller was focusing on interactions between Stone and Gates, the Trump deputy campaign chairman who pleaded guilty in February to two counts stemming from the Russia probe and is cooperating with Mueller.

Gates had a longtime business relationship with Manafort, the campaign’s chairman, who once ran a Washington lobbying firm with Stone. Manafort agreed to cooperate with Mueller after pleading guilty in September to conspiring against the U.S. The special counsel said he wasn’t always truthful with them in their conversations after the plea deal was reached, and there’s a hearing today in Washington to determine whether that’s the case.

In the indictment, Stone is alleged to have had advance notice that WikiLeaks would release personal email stolen from the account of Clinton campaign chairman John Podesta.