The Federal Bureau of Investigation, while under the aegis of the Justice Department, is nominally an independent organization, allowing it to remain nonpartisan. This explains in part the outrage on the left (and by some on the right) when F.B.I. director James Comey sent a letter Friday notifying Congress that the agency had renewed its investigation into Hillary Clinton’s private e-mail server, a case it had closed months earlier. Comey was immediately derided for his decision to send the letter with so few specifics so close to the election, effectively raising all sorts of flags and changing the campaign dialogue without explanation. Senator Harry Reid wrote a letter of his own, arguing that Comey’s “partisan actions” may have violated federal law. He also made the point of asking why the F.B.I. director didn’t give similar treatment to what he called “explosive information” linking Trump and his campaign staff to the Russian government.

Now, a new interagency mystery is raising questions about whether the F.B.I. has become politicized, just days before the presidential election. On Sunday, a long-dormant F.B.I. Twitter account suddenly sprung to life, blasting out a series of links to case files that cast the Clintons in a decidedly negative light. One tweet links to publicly available documents related to the agency’s investigation into Hillary Clinton’s private e-mail server, followed immediately by another tweet linking to the investigation of former general David Petraeus for compromising classified material—a jarring juxtaposition given the allegations against Clinton. Then, on Tuesday, the “FBI Records Vault” account—which had not tweeted at all between October 2015 and Sunday—published a link to records related to the 15-year-old, long-closed investigation into former President Bill Clinton’s pardoning of onetime commodities trader turned fugitive Marc Rich. The post, which was quickly retweeted thousands of times, links to a heavily redacted document that repeatedly references the agency’s “Public Corruption” unit—less-than-ideal optics for Hillary Clinton, who has spent her entire campaign fighting her image as a corrupt politician.

NBC News reported Tuesday that the release was “sent by the FOIA office under normal guidelines,” referring to a Freedom of Information Act request. Still, the timing seems questionable, given the swirl of accusations in recent days that the F.B.I. has effectively taken sides in the presidential election by publicizing information about Clinton while withholding information about Trump. The only item tweeted by the F.B.I. Records account related to the Republican’s campaign is a reference to Fred C. Trump, Donald Trump’s father, whom the tweet refers to as “a real estate developer and philanthropist.”

Clinton campaign spokesman Brian Fallon also noted the suspect timing. “Absent a FOIA litigation deadline, this is odd. Will FBI be posting docs on Trump's housing discrimination in '70s?” he tweeted.

Update: The F.B.I. commented Tuesday night on the release of documents related to the Marc Rich probe, telling Talking Points Memo that FOIA-related material are posted online automatically. The statement does not address questions about the Records Vault Twitter account:

The FBI's Records Management Division receives thousands of FOIA requests annually which are processed on a first in, first out (FIFO) basis. By law, FOIA materials that have been requested three or more times are posted electronically to the FBI’s public reading room shortly after they are processed. Per the standard procedure for FOIA, these materials became available for release and were posted automatically and electronically to the FBI’s public reading room in accordance with the law and established procedures.