Editor’s Note: Shanlon Wu is a former federal prosecutor and CNN legal analyst. He served as counsel to Attorney General Janet Reno. Follow him @shanlonwu. The views expressed in this commentary are his own. View more opinion at CNN.

CNN  — 

Deputy Attorney General Rod Rosenstein’s self-aggrandizing letter of resignation represents more than a contrast in writing styles with Robert Mueller’s letter to Attorney General William Barr in late March expressing his concern over Barr’s characterizations of Mueller’s report. The letters illustrate the difference between the public servants – one in search of the limelight, the other remaining true to his purpose. But Rosenstein and Mueller aren’t the only ones whose characters are on display. The attorney general’s actions after receiving Mueller’s letter also beg the question: Which kind of public servant will Barr be?

Shanlon Wu

Rosenstein’s letter reads like that of a middle-schooler whose favorite book is Bartlett’s Familiar Quotations. In only six short paragraphs, Rosenstein manages to quote Thomas Paine, Robert Jackson, Edward Levi, John Ashcroft and close with President Donald Trump’s “America first” exhortation.

While citing the words of others may be a weak attempt at modesty, the letter stands as an obvious effort to add grandiosity to his stature and career. Sadly for his legacy, Rosenstein appears doomed to learn that one’s own characterizations of their achievements often ring hollow. The likely epitaph for his long career at the Justice Department is now likely to be: “He Kept His Job.”

Mueller’s letter expresses his earnest concern to Barr that “(t)he summary letter the Department sent to Congress and released to the public late in the afternoon of March 24 did not fully capture the context, nature, and substance of this office’s work and conclusions.” Mueller also wrote: “There is now public confusion about critical aspects of the results of our investigation. This threatens to undermine a central purpose for which the Department appointed the Special Counsel: to assure full public confidence in the outcome of the investigations.”

For this most tight-lipped of public servants, the decision to make a permanent historical record of what amounts to disagreement with the attorney general’s actions cannot have been easy. As Mueller’s conduct throughout the special counsel investigation reveals, his focus was on modestly staying in his lane and doing a professional job. That he expressed his concerns about the way Barr handled his role in the investigation reflects what must have been a grave concern. Moreover, his suggestion that Barr release the report’s executive summaries show an unusual degree of assertiveness for a Justice Department prosecutor talking to the boss.

Barr’s response – or lack thereof – to Mueller’s letter speaks volumes. He apparently saw fit to bury it with nary a mention, allowing his own characterizations of the Mueller report to guide public perception for as long as possible. He even held a press conference before the release of the redacted report, which, naturally, avoided any substantial questioning about a report that no one had seen.

Barr is serving as attorney general of the United States for the second time. This time around he heads the Justice Department at a moment that poses historic challenges. A two-year investigation has concluded into potential wrongdoing by the President of the United States that has resulted in multiple convictions of Trump’s inner circle with a number of matters still ongoing.

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    Congress is demanding the unredacted Mueller report and testimony from the President’s White House counsel, Mueller and the attorney general. Barr’s decisions and actions about what to do next will reveal whether he is a true public servant, or a wannabe, motivated by currying favor with the President. But we cannot wait for these reveals. The question of whether Barr handled his role with integrity – and whether he will do so going forward – must be answered in public congressional hearings. Then it will be clear whether Barr is a Rosenstein or a Mueller.