Ex-Roger Stone aide appears before grand jury Friday after year-long subpoena fight

Ex-Roger Stone aide Andrew Miller emerged from his appearance before a federal grand jury in Washington D.C.– his testimony comes after a nearly year-long battle against a subpoena from special counsel Robert Mueller's office.

Miller's attorney Paul Kamenar told reporters after the two-hour testimony that Miller answered all the questions needed and prosecutors expressed "satisfaction" with his testimony.

Some of the questions from the grand jury, according to Kamenar, included Miller's 13-year working relationship with President Donald Trump's longtime friend and veteran political operative Roger Stone and any conversations about or information involving WikiLeaks and its founder Julian Assange. Kamenar said Miller didn't have any information about those topics to give.

"He's just like uncle Roger to me," said Miller, who arrived at the courthouse Friday morning with his lawyer in tow, donned aviator sunglasses, khakis and a chambray blazer with a vintage pocket square with a world fair theme.

Other questions involved Randy Credico and others known to have testified in association with Stone, Kamenar said, referring to the political humorist and radio show host whom Stone claims to have asked to act as an intermediary for him to contact Assange to confirm that the Wikileaks founder had a cache of information on Clinton during the 2016 campaign.. Credico appeared before Mueller's grand jury last year.

Kamenar said Miller and his legal team will provide government prosecutors with additional documents and email records concerning Miller’s work for Stone at the 2016 Republican National Convention.

Miller, who has been described by Stone once as his "wingman" has helped manage Stone's schedule, travel and media appearances. He also started and runs Stone's website "StoneZone.Com." Miller identifies himself as a libertarian and has said he did not support Trump’s candidacy, but he did accompany Stone to the 2016 Republican National Convention.

Mueller's prosecutors initially sought Miller's testimony while investigating Stone, who was indicted in January as part of the special counsel's probe. Stone was charged with seven counts which include obstruction, witness tampering and making a false statement. He's scheduled to stand trial in Washington D.C in November.

Miller has previously turned over requested documents to prosecutors and been offered limited immunity for his testimony but jumped into a year-long legal battle when the special counsel's team issued a subpoena compelling him to appear before Mueller's federal grand jury and related attempts to make him testify.

ABC News learned on Wednesday that Miller, after a series of court appeals, was directed by a judge in D.C. to appear before the grand jury on Friday.

After the testimony, Kamenar told reporters that Miller did not comply with the subpoena not because he didn't want to accommodate prosecutors but because he wanted to challenge the constitutionality of Mueller's appointment.

"Mr. Miller is a libertarian, and he strongly felt about this issue," Kamenar said.

On Thursday Stone himself appeared at the same Washington D.C. court to argue in favor of dismissing the case brought against him by Mueller's team and to get a less redacted version of the Mueller report. U.S. District Court Judge Amy Berman Jackson opted not to make any decisions on the matter yet.

Kamenar and Miller said they do not think Miller will be called as a witness in Stone’s upcoming trial scheduled for November.