WASHINGTON — Russia special counsel Robert Mueller is using at least two grand juries — in Virginia and Washington, D.C. — to advance a wide-ranging federal inquiry into possible coordination between President Trump's campaign and Moscow, a lawyer involved in the case said Friday.

As he investigates Russia's interference in the presidential election, Mueller may continue to use multiple panels or eventually consolidate those efforts in Washington, where the special counsel's team has only begun to use a grand jury in recent weeks.

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But the lawyer, who requested anonymity to discuss the matter, said both venues continued to be active in recent days.

The use of the grand jury located in Washington is potentially significant, analysts said, as it likely means investigators are probing activities that happened within that jurisdiction.

Mueller's team is investigating possible obstruction of justice related to the president's abrupt May 9 dismissal of FBI Director James Comey, and former National Security Adviser Michael Flynn's contacts with Russian ambassador Sergey Kislyak — all of which occurred in the District of Columbia.

Flynn was dismissed after misleading Vice President Pence and others about the content of his conversations with the ambassador, which did include talk of sanctions against Russia imposed by the Obama administration despite his denials.

By tapping a grand jury in Washington, former federal prosecutor Patrick Cotter said, "it appears that Mueller is working where the evidence leads him."

While Trump has denounced the Russia investigation as a "witch hunt," the use of these grand juries is a clear sign that Mueller's probe is intensifying and could go on for months or years.

The move would give Mueller, a former FBI director, broad authority to subpoena documents and compel witnesses to testify under oath.

Shortly after Mueller was appointed as special counsel, the former FBI director took control of an existing federal grand jury in Alexandria, Va., that had been examining Flynn's prior lobbying business involving Turkey.

Mueller's use of the Washington grand jury was first disclosed Thursday by the Wall Street Journal.

The apparent expansion of the inquiry appeared to take Trump's legal team by surprise.

John Dowd, Trump's lead outside attorney, said he had not been made aware of the Washington panel's involvement prior to the published report. But he believed that Trump was not a target of the inquiry.

"With respect to reports of a federal grand jury, I have no reason to believe that President Trump is being investigated,'' Dowd said.

Ty Cobb, special White House counsel, said that he, too, had been unaware of the Washington panel until late Thursday, but pledged cooperation.

"The White House favors anything that accelerates the conclusion of (Mueller's) work fairly,'' Cobb said. "The White House is committed to fully cooperating with Mr. Mueller.''

Trump has not specifically addressed the existence of second grand jury. But at a Thursday night rally in West Virginia, he continued to characterize the overall investigation as a hoax.

Cotter, the former federal prosecutor, said Mueller's use of multiple panels in a wide-ranging investigation is not surprising when investigative interests straddle multiple jurisdictions.

"When you are looking to subpoena documents and reach potential witnesses, wherever they may be, you're using the grand jury,'' Cotter said. "It shouldn't be a surprise. What the hell do you think he's been doing all this time.''