The Justice Department announced Wednesday the appointment of Robert Mueller as special counsel to oversee the investigation of Russian interference in last year's U.S. presidential election.

So who is Robert Mueller?

Mueller, a Republican, was the sixth director of the Federal Bureau of Investigation, serving for 12 years. He was first appointed by President George W. Bush in 2001, taking over the FBI just a week before the September 11 terrorist attacks. He was confirmed 98-0 by the Senate, which then had a narrow Democratic majority.

"Bob Mueller's experience and character convinced me that he's ready to shoulder these responsibilities," Bush said. "Agents of the Bureau prize three virtues above all: fidelity, bravery and integrity. This new Director is a man who exemplifies them all."

President Obama asked him to stay on two years past the 10-year term limit, which the Senate approved in 2011. Mueller left the FBI in 2013 and was replaced as director by James Comey.

Mueller was born in New York City on August 7, 1944. He received his bachelor's degree from Princeton University in 1966, a master's degree in international relations from New York University in 1967 and his law degree from the University of Virginia School of Law in 1973.

During the Vietnam War, Mueller enlisted in the Marines. "I have been very lucky," he later told his law school's alumni magazine. "I always felt I should spend some time paying it back."

Mueller was wounded in combat during his service. He earned a Bronze Star, two Navy commendation medals, the Purple Heart, and the Vietnamese Cross of Gallantry.

After a few years working as a litigator, Mueller went to work for the U.S. Attorney for the Northern District of California for six years. In 1982, he went to Boston to work in the U.S. Attorney's Office for the District of Massachusetts, prosecuting terrorism, fraud and public corruption cases.

In 1986, Mueller rose to U.S. attorney for Massachusetts, succeeding future Bay State Gov. William F. Weld. He left for private law practice after a year but was appointed assistant attorney general for the criminal division by President George H.W. Bush in 1990.

President Clinton appointed Mueller U.S. attorney for the Northern District of California in 1998, putting him in charge of the office where he began his public service. The second President Bush elevated him to acting deputy attorney general upon taking office in 2001, a position in which he served until May of that year. Mueller was nominated for FBI director that July.

Mueller and Comey were linked once before when they both threatened to resign if the Bush White House overruled the Attorney General John Ashcroft and the Justice Department on warrantless wiretapping. Justice had held that domestic wiretapping was unconstitutional. Comey was deputy attorney general at the time.

After the FBI, Mueller oversaw an investigation into the NFL's handling of Baltimore Ravens running back Ray Rice's domestic violence probe. He found there was no evidence the league had seen the elevator video of Rice knocking out his then girlfriend and covered it up.

"Our nation is grounded on the rule of law, and the public must be assured that government officials administer the law fairly," said Deputy Attorney General Rod Rosenstein in the statement announcing the special counsel appointment. "Special Counsel Mueller will have all appropriate resources to conduct a thorough and complete investigation, and I am confident that he will follow the facts, apply the law and reach a just result."