Former FBI Director Robert Mueller, special counsel will take over FBI Russia campaign interference investigation

Bowing to public and Congressional pressure, Deputy U.S. Attorney General Rod Rosenstein appointed former FBI Director Bob Mueller on Wednesday to be a special counsel overseeing the investigation into Russian interference in the 2016 campaign, Justice Department officials said.

Mueller will take command of the prosecutors and FBI agents who are working on the far reaching Russia investigation, which spans multiple FBI field offices on both coasts.

"In my capacity as acting Attorney General, I determined that it is in the public interest for me to exercise my authority and appoint a Special Counsel to assume responsibility for this matter," Rosenstein said in a statement. "My decision is not a finding that crimes have been committed or that any prosecution is warranted. I have made no such determination. What I have determined is that based upon the unique circumstances, the public interest requires me to place this investigation under the authority of a person who exercises a degree of independence from the normal chain of command."

Mueller led the FBI for 12 years under Presidents George W. Bush and Barack Obama. He is second only to J. Edgar Hoover for longest tenure for an FBI chief.

Mueller has agreed to resign from his private law firm in order to avoid any conflicts of interest, the AG's office said.

Reactions of the former FBI director leading the Russia investigation:

A spokesperson for the Department of Justice told NBC News the White House's Counsel's Office was informed of the appointment of a special counsel after the order was signed this afternoon, but did not provide a specific time.

The FBI, with the help of the Treasury Department, the CIA and other agencies, has been examining evidence of possible contacts, money transfers and business relationships between a variety of President Trump's associates and Russian officials, sources say.

The investigation goes well beyond a possible American connection, to include how Russian intelligence services carried out the campaign of fake news and leaking hacked emails that intelligence officials say was meant to hurt Hillary Clinton and benefit Trump.

But the question of whether Trump associates colluded with Russia is consuming public interest. No evidence has surfaced publicly linking Trump himself to the Russian interference effort.

Related: Here Are Three Ways to Have an Independent Russia Inquiry

Rep. Jason Chaffetz, R-Utah and the chairman of the House Oversight Committee, called Mueller a "great selection."

Senate Minority Leader Chuck Schumer said a special counsel had been "very much needed" and that Rosenstein had "done the right thing."

"Former Director Mueller is exactly the right kind of individual for this job," Schumer said in a statement. "I now have significantly greater confidence that the investigation will follow the facts wherever they lead."

And House Minority Leader Nancy Pelosi said Mueller was "a respected public servant of the highest integrity," but said more still needed to be done.

"The Trump administration must make clear that Director Mueller will have the resources and independence he needs to execute this critical investigation," she said in a statement.

"A special prosecutor is the first step, but it cannot be the last. Director Mueller will still be in the chain of command under the Trump-appointed leadership of the Justice Department," she said. "He cannot take the place of a truly independent, outside commission that is completely free from the Trump Administration's meddling. "

See images of former FBI Director Robert Mueller

Former Attorney General Eric Holder said, "As long as his character is appropriately defined and he is properly resourced, this is a good move."

"There is much that warrants investigation involving people at the highest levels of the executive branch," Holder said in a statement. "I'm confident he can and will do that. The country is owed that."

The last special counsel was Patrick Fitzgerald, who was tapped in 2003 to investigate the leaking of a CIA operative's name.

Under Justice Department regulations issued in 1999, a special counsel is not fully independent of the Justice Department.

According to a Congressional Research Service report, the attorney general — or in this case, Rosenstein, since Attorney General Jeff Sessions has recused himself — must be notified of any specific actions the special counsel intends to take, and has the ability to countermand those proposed actions.

Modern special counsels have less independence than the special prosecutors employed during the Watergate investigations of the 1970s, who were appointed under a law that has now expired.