U.S. Attorney General William Barr jokes with Deputy Attorney General Rod Rosenstein on May 09, 2019 in Washington, DC. (Photo by Chip Somodevilla/Getty Images)
Washington CNN  — 

Deputy Attorney General Rod Rosenstein, who appointed special counsel Robert Mueller to investigate Russian interference in the 2016 presidential election, said goodbye to the Justice Department on Thursday.

“Justice is in good hands,” Rosenstein told a packed crowd of current and former department officials, friends and well-wishers gathered in the department’s Great Hall.

While not directly mentioning the Russia investigation he led for nearly two years or some of its more controversial moments, the deputy attorney general said Thursday that it’s “most important to follow the rules when the stakes are highest.”

Rosenstein’s farewell celebration came two years to the day after the firing of FBI Director James Comey by President Donald Trump that led to Mueller’s appointment.

At the gathering, Rosenstein extolled the work of federal prosecutors, the power they wield and how “allegations carry severe consequences.”

“The rule of law requires us to tune out the news cycle,” Rosenstein said, mentioning the importance of prosecutors avoiding “confirmation bias” and how the “most dramatic moments may have very little impact” at the end of the day.

Thursday’s event for Rosenstein was something of a “who’s who” of high-profile characters within the Trump administration, including Attorney General William Barr, former Attorney General Jeff Sessions and former White House Counsel Donald McGahn – a central witness in Mueller’s obstruction of justice investigation against Trump.

Barr praised Rosenstein’s “exceptional intelligence” and “upbeat spirit,” joking that a debate has been raging about whether he or Rosenstein can make the most “deadpan expression” – a reference to their faces at Barr’s news conference prior to the Mueller report’s release.

Sessions praised his deputy for steering the department through tough times, noting that Rosenstein didn’t ask to oversee the “so-called collusion investigation,” but “the baby fell to Rod” – a nod to Barr calling the Mueller report “my baby” while testifying before lawmakers last week.

“Things were often a bit not normal,” Sessions added, recounting a dinner last year he and Rosenstein had in the midst of one of Trump’s flare-ups. He quipped, “Our run exceeded my expectations – considerably!”

Pressure cooker

After nearly 30 years of service in various roles at the Justice Department, Rosenstein became a household name over the last two years of overseeing the Russia probe, while also supervising the FBI and US attorney’s offices, and managing a hefty portfolio of the criminal and national security divisions within the broader department.

At the same time, the lifelong Republican fended off months of attacks from Trump’s GOP allies about his handling of the Russia investigation, frequently dealing with squabbles over access to classified documents and other rarely shared materials – all of which culminated in a small but vocal group of lawmakers laying the initial steps for his impeachment last year. The effort to oust him proved unsuccessful but it served as emblematic of the pressure cooker environment he often faced.

Rosenstein has not publicly announced what he’ll be doing next. The nomination of his successor, Jeffrey Rosen, was successfully voted out of the Senate Judiciary Committee along party lines Thursday morning and awaits confirmation from the full Senate.

Filling the shoes of Sessions – who’d stepped aside from overseeing the Russia investigation given his role as a Trump campaign surrogate – Rosenstein had been on the job as the No. 2 for only two weeks before the President ordered him to write a memo justifying firing Comey.

He complied, but in a chaotic week that followed, Rosenstein was upset that the memo was initially portrayed by the White House as the reason for Comey’s termination and, according to some former FBI officials, Rosenstein mused about wearing a wire to record the President and ousting Trump from office through the 25th Amendment – dramatic steps that were never acted on and episodes Rosenstein has said were mischaracterized, but when later made public almost cost him his job.

In the end, he appointed Mueller as special counsel, and then sat for an interview – teeing up what would prove to be his delicate two-year balance as both witness and supervisor of the special counsel’s investigation into possible obstruction of justice.

Trump’s temper periodically flared against Rosenstein, dismissing him at times as merely the “deputy” who appointed Mueller “from Baltimore” (though he’s from Philadelphia) and tweeting out a picture of him behind bars.

Republicans on Capitol Hill also regularly took him to task in Trump’s defense, and he fought back – warning that the Justice Department was “not going to be extorted” amid the threats that he could be impeached.

Rosenstein, nevertheless, in his resignation letter to Trump, spoke fondly of the President’s “courtesy and humor” in their personal conversations.

And ultimately, Mueller did not reach a decision about whether Trump had obstructed justice, but Rosenstein helped clear the President, agreeing with Barr’s assessment that the evidence wasn’t sufficient to establish a prosecutable crime.

“It’s not our job to render conclusive factual findings,” Rosenstein said in a fiery speech last month, defending his handling of the investigation. “We just decide whether it is appropriate to file criminal charges.”

CNN’s Caroline Kelly contributed to this report.