Special counsel Robert Mueller's office has never contacted former Trump campaign adviser Roger Stone during its 19-month investigation of the Russian government's efforts to interfere with the 2016 U.S. presidential election, Stone and his attorney said in interviews Tuesday.

Stone has told reporters in the past that he's had no contact with Mueller, and that remains true as 2019 approaches.

"Nothing's changed," Stone said during an interview with NBC News on Capitol Hill while he was protesting with InfoWars' Alex Jones outside a hearing where Google CEO Sundar Pichar answered lawmakers' questions about alleged political bias.

Stone's ties to President Donald Trump go back four decades. He worked for the Trump campaign as an adviser for a short time in 2015 and continued as an informal adviser after leaving his role. During the summer of 2016, he made several public statements that seemed to indicate he had spoken to WikiLeaks founder Julian Assange or could be interpreted to mean he had advance knowledge that WikiLeaks was going to release hacked Democratic emails, which he denies.

More than 10 of his associates have now been called before a grand jury in D.C. to answer questions from Mueller's prosecutors related to Stone and WikiLeaks.

Stone said several months ago that he expects to be indicted. Even though he says he has not been contacted by Mueller's team, he wrote in an August email to supporters that "Robert Mueller is coming for me" and that Mueller's investigators are "examining every aspect of my personal, private, family, social, business and political life."

Legal analyst Daniel Goldman said based on the number of witnesses interviewed there is no question the special counsel is conducting a serious and intensive investigation into Stone, but that his appears to be a tricky case and it is by no means a certainty he will be charged.

"In order for Stone to be charged with conspiring with others to interfere with the fair and proper administration of the 2016 election, the special counsel must determine that he took specific actions to coordinate with WikiLeaks and assist in the dissemination of the hacked emails… If he merely learned about it and did not take any steps to assist or coordinate, then he did not commit a crime," said Goldman, an NBC News legal analyst and former assistant U.S. attorney for the Southern District of New York.

Stone testified before the House Intelligence Committee in September 2017 about Russia and Trump and Tuesday he stood by his testimony saying everything he told the committee "is true and accurate." He noted he supplemented his testimony with four documents at the request of the committee, which "bolsters my testimony."

In one of the supplemental documents he provided the committee he named Randy Credico as his backchannel to WikiLeaks. When asked Tuesday why he didn't initially name Credico, Stone said he "feared professional reprisal against [Credico] in the workplace, yet I was persuaded by the committee and my own attorneys to identify him which I did." Stone and Credico texted about WikiLeaks during the summer and fall of 2016, with Credico texting at one point he was "best friends" with Assange's lawyer. Credico has repeatedly denied that he got any inside information from WikiLeaks.

In another supplemental document for the committee Stone acknowledged a brief meeting in Florida with a Russian named Henry Greenberg during the campaign.

"The question before House Intelligence Committee was did I meet with any representatives of the Russian State. [Greenberg] does not qualify," he said Tuesday.

Stone recently declined to speak with the Senate Judiciary Committee in its Russia probe.

During the heat of the campaign in June 2016, Assange announced he had emails damaging to Clinton. Communications reviewed by NBC News show that Stone and others made efforts to try to learn details about what was coming. The Friday before the Democratic National Convention, Assange released the first batch of DNC emails.

On Aug. 8, 2016, Stone told the Southwest Broward Republican Organization, "I actually have communicated with Assange. I believe the next tranche of his documents pertain to the Clinton Foundation but there's no telling what the October surprise may be."

On Aug. 21, 2016, he tweeted, "Trust me, it will soon [sic] the Podesta's time in the barrel." Two months later Assange began releasing Clinton campaign chairman John Podesta's emails. His attorney notes that this tweet followed a series of tweets about Podesta the week before. Podesta was the subject of Republican opposition research during the campaign and some in Stone's camp have said that it was not out of the blue that Stone would text about Podesta.

Stone has been saying for months that the statements he made in 2016 were political bluster in the heat of a campaign, and his attorney said that media focus on them takes them out of context. Stone maintains he has never spoken to Assange, and while he may have asked people to find out details about the content and timing of WikiLeaks' publication of Democrats' emails that would be damaging to Clinton, he in no way colluded with WikiLeaks and did nothing illegal to try to help the campaign of Donald Trump.

In the wide-ranging interview with NBC News Stone said he never spoke to candidate Trump about WikiLeaks during the campaign.

Stone's friend Jerome Corsi has been questioned by Mueller's team and was offered a plea deal for lying to investigators, which he rejected. Corsi has sued Mueller and other government agencies for allegedly trying to blackmail him into lying. Asked what he thinks about Corsi's approach, he said, "I wouldn't do it the same way."

A spokesman for the special counsel's office declined to comment.

Michael Cappetta reported from Washington, D.C.