Mueller's team put in a formal request for the transcripts, although the date of the request is in question, as sources have told different media outlets different stories. ABC reports that the request was lodged on Wednesday, while the Washington Post reports it was last Friday.
The special counsel already had an unofficial transcript of Stone's testimony, which was given in September 2017, and so legal experts believe that the request for an official transcript indicates he is getting ready to charge Stone, as he cannot do so without an official copy.
Democrats on the House Intelligence Committee have maintained that Stone lied in his testimony. Trump's former personal lawyer, Michael Cohen, was recently sentenced to more than three years in prison in part over a charge of lying to Congress.
ABC News on Thursday obtained a letter from Stone's legal team to committee chair Devin Nunes (R-CA), demanding that the transcript of his testimony be released to the public.
"In order for Mr. Stone to properly and effectively defend himself from the partisan attacks that have only been made possible by the committee's ongoing retention in secret of the only verified and accurate record of his testimony, Mr. Stone must be immediately provided this record, in full and without any arbitrary restrictions," Grant Smith, one of Stone's attorneys, said.
"Without regard to any decision or action the committee may take in response to a request by the [special counsel], or any other person or agency, for a copy of the interview transcript, either in whole or in part, Mr. Stone hereby demands the full and immediate release to the general public of the transcript, such that the American citizenry and the world are able to evaluate for themselves Mr. Stone's veracity," he added.
Stone's team responded to the committee's decision, telling ABC News, "With all the unsupported, wild accusations of the Democrats on the committee and the media frenzy surrounding the same, it is not surprising that the special counsel's office has asked for access to the transcript. In fact, we had believed that this had taken place a while ago."
The committee has already voted to release dozens of transcripts of testimonies given in connection to the special counsel's probe of allegations of collusion between members of Trump's campaign and the Russian government. Those documents aren't expected to be released until January, but Representative Adam Schiff (D-CA) has promised to speed up the process after he takes the role of committee chair once Democrats take control of the House.