Washington (CNN) - Roger Stone associate Andrew Miller is still needed by a federal grand jury conducting an ongoing criminal investigation started by special counsel Robert Mueller, according to an appeals court filing Thursday.
The Justice Department's assertion appears to confirm that more criminal charges are still possible related to Miller's requested testimony, and that a grand jury used by Mueller's team is still at work. Mueller has transferred the grand jury to federal prosecutors in Washington.
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"The need for expedition in this grand jury matter -- which arises from a subpoena served more than a year ago -- outweighs the only harm that Miller claims, which is the burden of traveling to Washington, D.C. (at government expense) to testify and the attendant risk of his case becoming moot," prosecutors wrote in the court filing Thursday." Delaying his testimony, on the other hand, would delay an ongoing criminal investigation, to the detriment of the government and the public at large."
The question of what prosecutors still might need from Miller has hung over him since Stone was indicted by the grand jury in January and Mueller concluded his investigation in March. Stone has pleaded not guilty and is headed to trial later this year, and prosecutors at this point are not allowed to use the grand jury to build out evidence against him for that trial.
Miller was held in contempt of court last summer for refusing to testify to a grand jury, presumably about Stone, WikiLeaks and the distribution of hacked Democratic documents during the 2016 campaign. He's been challenging his grand jury subpoena and Mueller's appointment for months, losing in the courts at every turn. Most recently, Miller indicated he wanted to appeal to the Supreme Court, but on Thursday prosecutors said he should not be given more leeway from judges to appeal.
If he continues to refuse to testify and has exhausted his appeals, Miller should be jailed, a judge has said.