The F.B.I. team had plowed through 50,000 Hillary Clinton e-mails found on Anthony Weiner’s laptop in less than one week. Yet on Saturday night, November 5—less than three days before polls opened for Election Day, 2016—there were 3,000 more to review. Pizza was ordered. Around 2 a.m. the job was done, and an e-mail was written informing Director James Comey that nothing new or incriminating had been discovered.

The senior agent who led that review and wrote that e-mail was not publicly identified at the time. Nor when he became a top investigator for Robert Mueller. Now, though, Peter Strzok is unhappily on the verge of becoming a household name, thanks to a different electronic-messaging mess: private texts he exchanged calling Donald Trump “an idiot” and a “douche.” The White House, congressional Republicans, and their media allies are trying to make Strzok the poster boy for F.B.I. bias in an attempt to undermine Mueller’s probe of Trump.

Which would be funny if the stakes weren’t so high, and the games being played weren’t so cynical. “The F.B.I. is anti-Clinton, period,” said one former top agent. “It’s not the Clintons’ politics, but the rule-bending and -breaking—Travelgate, Whitewater, Monica, the server—and Hillary acting as if she’s above the law. I have a lot of friends who worked the Hillary investigation, and they freakin’ hated Hillary’s guts.” As for Strzok, clearly he preferred Clinton to Trump—but as a civilian, not as an investigator. “I’ve known Pete since 2004. He worked for me,” said Michael Steinbach, the former executive assistant director of the F.B.I.’s national security branch, who worked closely with Comey on the Clinton and Russia investigations. “Pete was a rock star as an investigator, and was on tap to be the next assistant director of counterintelligence. He never let any personal views taint his work.”

The tarring of Strzok (pronounced “Strock”) is just the latest chapter in the long, ugly attempt to weaponize and politicize the F.B.I. in connection with the 2016 campaign. Comey set the process in motion with his controversial decision to clear yet castigate Clinton for her use of a private e-mail server when she was secretary of state. Three months later, Weiner’s laptop was seized as part of an investigation into his sexting with a minor. Rudy Giuliani and James Kallstrom, a former boss of the F.B.I.’s New York field office, claimed that revelations damaging to Clinton would soon be unveiled, and that New York F.B.I. agents were angry at Comey for concealing the truth. Conservative websites, particularly True Pundit, claimed to have sources inside the New York office. “It is going to be ironic if it turns out there was a leaker in the New York office helping Trump,” said Asha Rangappa, a former F.B.I. counterintelligence agent in New York. “Mueller will find that person, and then all the hoo-ha that’s being made about Strzok is going to be nothing.”

In the heat of the closing days of the campaign, one narrative held that the chatter forced Comey’s hand: concerned that rogue agents might leak information about the contents of Weiner’s laptop, the then F.B.I. director notified Congress that he was reopening the Clinton probe, blowing an enormous hole in the Democrats’ campaign.

But that theory may be overblown. Steinbach insists that it was Comey, in his probity and idiosyncrasy, that drove the story. “The conspiracy theory may sound good, but in reality, when you know the volume of what we thought we had—which turned out to be wrong—and the likelihood we would find new e-mails that were classified, which would then need to be kicked out to N.S.A. or C.I.A. for the classification review, we thought this would be probably a couple-months-long process,” he said. “Giuliani and Kallstrom had about as much relevance to what’s going on in the bureau as my daughter. They could not have influenced Comey. He’s got an independent streak a mile wide.”