WASHINGTON (AP) — The former chief of staff to former Vice President Mike Pence has testified before a federal grand jury investigating the Jan. 6, 2021, assault on the U.S. Capitol, a person familiar with the matter said Monday.

Marc Short, a close aide to Pence, was at the Capitol on the day of the siege and was with the vice president as he fled his post presiding over the Senate and hid from rioters who had stormed the building and called for his hanging.

Short appeared before the grand jury after receiving a subpoena to do so, according to the person, who insisted on anonymity to discuss an ongoing investigation. The appearance was first reported by ABC News, which said it took place last week. A spokesman for the U.S. attorney's office did not immediately return a phone message and email seeking comment Monday.

On CNN Monday evening, Short confirmed the appearance, saying, "I did receive a subpoena for the federal grand jury and I complied with that subpoena."

He said it was his "only appearance before the grand jury" but declined to speak further about the questioning.

It was not immediately clear what Short was asked during his grand jury appearance, but the Justice Department has been investigating wide-ranging efforts by allies of former President Donald Trump to undo the results of the 2020 presidential election, including through the creation of slates of fake electors in battleground states intended to subvert the vote count.

Attorney General Merrick Garland told reporters last week that "no person is above the law" and described the investigation into the attack on the Capitol as the most important and most sweeping probe in the Justice Department's history.

Short has also cooperated in a separate House committee investigation of the insurrection.

In video testimony played at one of the panel's hearings last month, Short recalled that Pence had communicated to Trump "many times" that he did not agree with efforts to get him to overturn the election results, including by rejecting electors or by simply declaring Trump the winner.

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