Rachel Brand, the third-ranking official at the Justice Department, will step down from the job, NBC News reported Friday.
The New York Times first reported her decision.
The associate attorney general's move follows President Donald Trump's repeated attacks on the department for its role in the probe into Russian interference in the 2016 election.
Crucially, Brand may have overseen special counsel Robert Mueller's Russia probe if Trump decided to fire deputy attorney general Rod Rosenstein, who he has repeatedly criticized. Attorney General Jeff Sessions recused himself from the investigation.
Brand served only nine months in the role and will take a job in the private sector, NBC and the Times reported. She received a job offer she could not turn down, according to NBC.
Trump's criticism of how U.S. law enforcement agencies handled investigations into HIllary Clinton's email server and whether the Trump campaign colluded with Russia have ramped up in recent weeks. Last week, he allowed the release of a House Republican memo that alleges political bias related to the Russia probe.
The president has repeatedly criticized Sessions, an ally and campaign advisor, for stepping back from the Russia investigation.