Who is Robert Mueller?

And on Thursday, the public is expected to see the release of a redacted version of Mueller's special counsel report on President Donald Trump and Russian interference in the 2016 election, a moment that will mark the culmination of this latest act in Mueller's decades-long legal career.

Vietnam to law enforcement

Born in 1944, Mueller joined the Marines in 1966 and fought in the Vietnam War. He was awarded a Bronze Star, a Purple Heart, the Vietnamese Cross of Gallantry and two Navy Commendation Medals.

Mueller attended Princeton University for his undergraduate degree, New York University for an M.A. and the University of Virginia for his law degree. After graduation, he became an associate attorney at a law firm before joining the US attorney's office in the Northern District of California. He rose through the ranks of the Justice Department over the years, with stints in the private sector before coming back to the Justice Department under the homicide section of the office for the US attorney in DC and then again becoming a US attorney in the late 1990s.

Mueller found himself in some of the most well-known cases of his time, from overseeing the prosecutions of Panamanian dictator Manuel Noriega and Mafia kingpin John Gotti to leading an investigation into the Lockerbie bombing.

Director Mueller

President George W. Bush tapped Mueller to lead the FBI shortly into his presidency, and Mueller was confirmed unanimously in a Senate vote of 98-0, taking over the FBI just days before September 11, 2001.

As a member of the Bush administration, Mueller was a key leader on post-9/11 security policy, and like other top Bush administration officials, he testified before Congress in the lead up to the Iraq War, saying he was concerned Iraqi leader Saddam Hussein "may supply terrorists with biological, chemical or radiological material."

Post-9/11 surveillance programs would later become a flashpoint following the disclosures by Edward Snowden, and in an exit interview with CNN, Mueller offered a broad defense of their collection methods.

But while still on the job, Mueller found himself in a major dispute about domestic spying, when he backed then-Deputy Attorney General James Comey in a fight with the White House over renewal of a surveillance program. In 2007, Comey delivered bombshell testimony before Congress about the 2004 dispute and praised Mueller as "one of the finest people" he had ever met. Mueller's notes from the time backed up Comey's account, and in response to a records request from The New York Times, documents showed Bush made some changes to authorize the surveillance program following the showdown Comey and Mueller had with the White House officials.

Mueller was so highly regarded on both sides of the aisle that when the end of his ten-year term as director came, then-President Barack Obama took the rare step of asking Mueller to stay on, and the Senate obliged in a unanimous vote of 100-0. The extension made Mueller the longest-serving FBI director since its infamous leader, J. Edgar Hoover. At the end of the extension, Obama tapped Mueller's old Bush administration colleague, Comey, to take over the FBI.

Special counsel

And the rest is very recent history.

A few weeks after Trump took office, Comey confirmed the existence of an investigation into coordination between Trump's campaign or associates and Russia to interfere in the 2016 election. Trump went on to fire Comey as FBI director in May 2017. It emerged shortly thereafter that Comey kept contemporaneous memos of his private conversations with Trump, who Comey alleged pressured him on ongoing FBI investigations (Trump denied the allegations and has long boasted about firing Comey, who Trump calls a liar).

The revelation led to Deputy Attorney General Rod Rosenstein appointing Mueller to lead a special counsel investigation into Russian interference in the 2016 election and other crimes uncovered in the course of the investigation, which included looking into potential obstruction of justice by Trump.

Mueller brought on a team of investigators, including some very well-known prosecutors, to handle the massive investigation and worked in intense secrecy for the duration of his time as special counsel.

Mueller's appointment was initially met with bipartisan praise, but Trump and his allies regularly went after Mueller and his team as politically biased and conducting a "witch hunt." The special counsel team brought charges against 37 people and entities, and concluded its work in March 2019. Attorney General William Barr said Mueller authored a nearly 400-page long report, interviewed about 500 witnesses and "made 13 requests to foreign governments for evidence."

In his initial summary of Mueller's report, Barr said the special counsel did not find a conspiracy between Trump's associates or campaign and the Russian government, and he said Mueller left open the question of obstruction of justice, which he concluded Mueller did not find sufficient evidence to support.

After weeks of back-and-forth between Barr and Congress, the Justice Department said it expects to provide a redacted version of Mueller's report this Thursday.

As for Mueller, his job as special counsel will be done, and the 74-year-old former FBI director can move on, although there's always the possibility he will have to go back to Capitol Hill and speak to the public for the first time about his work.