A former aide to Trump confidant Roger Stone has agreed to testify this week before a grand jury initially used in special counsel Robert Mueller's Russia investigation, his attorney said Wednesday.

Andrew Miller, who has fought the subpoena for nearly a year, is scheduled to appear Friday before a grand jury in Washington. The decision to testify comes after an appeals court rejected Miller's challenge of Mueller's authority and a federal judge on Wednesday denied his last effort to avoid going before the grand jury.