Neither Mueller's name nor the Russia investigation he leads was mentioned during the ceremony for Sessions, who was forced out last November by President Donald Trump.
But the tumult of the last two years, which included Sessions' recusal from an investigation into the Trump campaign and the subsequent appointment of Mueller by Deputy Attorney General Rod Rosenstein, was evident even as the ex-attorney general was saluted for his leadership.
"No attorney general's tenure goes exactly as planned. Unexpected developments always arise," said Rosenstein, likely an oblique reference to Sessions' unceremonious departure one day after the midterm elections. Rosenstein also read a letter from Sessions' daughter wrote during the confirmation process in which she said her father endured "relentless" attacks from critics without returning fire.
The ceremony, during which Sessions was presented with the chair he used during Cabinet meetings, unfolded as Mueller prepares to deliver his final report on the investigation to new Attorney General William Barr, who also spoke warmly of Sessions.
The event brought together two Justice Department officials who have been attacked by the president - Rosenstein is expected to leave his position soon - and a third, Barr, who may also find himself fending off attacks on the Justice Department, depending on Mueller's findings.
Sessions was lauded during the ceremony for his emphasis against violent crime, opioid addiction and illegal immigration - priorities in line with the president's agenda.
But he endured scathing attacks from the president for most of his tenure following his decision in March 2017 to recuse from the Justice Department's investigation into possible ties between Russia and the Trump campaign. He was asked to resign in November 2017 and replaced first by his chief of staff, Matthew Whitaker, and then on a permanent basis by Barr.
Sessions himself spoke briefly, describing his time as attorney general as the "the most meaningful months in my professional life."
"It's been an honor for me to serve you," he said.
Rosenstein ticked off a number of attorneys general who served shorter tenures than Sessions. Those include Barr, who spent just over during his first stint as attorney general in the early 1990s.
"An attorney's general's service is measured by accomplishments, not by length of service," Rosenstein said.
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