The newly appointed second-in-command at the US Justice Department faced a weighty task just two weeks after taking office: writing the rationale for firing FBI Director James Comey.
Deputy Attorney-General Rod Rosenstein argued the case for Comey's sacking in a three-page memo to Attorney-General Jeff Sessions on Tuesday.
President Donald Trump acted swiftly to dismiss the director within hours.
Rosenstein cited Comey's controversial public statements about the bureau's investigation into Democratic presidential candidate Hillary Clinton's use of a private email server while secretary of state.
"It is a textbook example of what federal prosecutors and agents are taught not to do," Rosenstein wrote of Comey's comments.
The Department of Justice and the FBI did not comment on Tuesday.
Comey's firing will likely be seen as further evidence of Washington's hyper-partisan upheaval.
Rosenstein has drawn fire from Democrats who allege political motives in the White House decision to dismiss Comey and particularly its timing.
"Why did it happen today?" asked Senate Democratic Minority Leader Chuck Schumer.
"We know the FBI has been looking into whether the Trump campaign colluded with the Russians ... Were those investigations getting too close to home for the President?"
The rationale for canning Comey, however, came from a 26-year Justice Department veteran widely viewed as uncommonly nonpartisan.
Named as Maryland's top prosecutor by President George W. Bush, Rosenstein stayed in office through the Obama administration.
Rosenstein was the longest-serving US attorney when nominated by Trump in January.
When confirmed by the Senate, he enjoyed overwhelming support - a 94-6 vote - despite the deeply divided culture of today's Washington.
Bonnie Greenberg, a federal prosecutor in Maryland, says Rosenstein is admired as a rare career prosecutor who can insulate himself from political pressure.
"He only does something if he thinks it's right," said Greenberg, who worked with Rosenstein for 11 years.
Many in the Justice Department saw Rosenstein's appointment as a counter-balance to the extreme partisanship surrounding accusations of Russian interference in last year's election. And he was immediately swept into that fray.
Before being confirmed by the Senate, some Democratic members asked him to pledge to appoint a special independent prosecutor to investigate allegations of collusion between the Trump campaign and Russian officials.
He was easily confirmed despite rebuffing those demands.
Some Republicans have been angered by Comey's public statements about the FBI investigation into possible ties between the Trump campaign and Russia.
But Rosenstein's criticism of Comey focused on actions seen to have damaged Democratic candidate Clinton.
Rosenstein focused in particular on Comey's news conference last July, when the director announced his conclusion that Clinton should not be prosecuted - while at the same time publicly bashing her use of a private email server for sensitive US government business.
That day, Rosenstein wrote, Comey usurped the authority of the US Attorney General - who has authority over whether prosecutions should proceed, based on the quality of FBI investigations.
Comey also violated longstanding practice by "gratuitously" releasing damaging information about Clinton - even as he acknowledged the evidence against her was insufficient to warrant continued investigation, Rosenstein wrote.
"We do not hold press conferences to release derogatory information about the subject of a declined criminal investigation," Rosenstein wrote, adding that Comey "laid out his version of the facts for the news media as if it were a closing argument but without a trial".
US Senator Mark Warner of Virginia, the top Democrat on the Senate Intelligence Committee, said the timing of Comey's firing was suspect - coming so long after the election of Trump and Comey's alleged mishandling of the case.
He directly criticised Rosenstein.
"I am very disappointed with this deputy attorney general, who I was told had a good reputation," he said.
"But signing this letter saying he recommends firing Comey because of Comey's actions with Hillary Clinton nine months ago or 10 months ago? That doesn't pass any smell test."
