After initial apprehension about investigating Hill’s charges that Thomas had sexually harassed her while he was her boss at the Equal Employment Opportunity Commission, then–Senate Judiciary Committee Chairman Joe Biden requested that the FBI look into the matter. FBI investigators interviewed both Hill and Thomas, who categorically denied Hill’s charges.

Read Benjamin Wittes on why he admires—but wouldn’t confirm—Brett Kavanaugh.

The FBI investigators were less than thorough, according to Jill Abramson and Jane Mayer in Strange Justice, their account of the Thomas confirmation battle. In an early interview with James Brudney, a Democratic staffer, Hill described in detail her now-infamous encounters with Thomas. She described Thomas saying out loud in the office “Who has put pubic hair on my Coke?” and claimed that he discussed “pornographic materials depicting individuals with large penises or large breasts involved in various sex acts.” She said he discussed the porn star “Long Dong Silver” and bragged about the size of his penis.

Hill also mentioned these explicit charges in her Senate testimony—but they did not appear in the official FBI report, and that absence was used against her.

According to Mayer and Abramson, the two agents who interviewed Hill, John B. Luton and Jolene Smith Jameson, “had been ordered by the Republicans in Washington to watch her testimony,” and were “supposed to note any discrepancies between her answers to the committee and her initial interview with them.” After Hill’s Senate testimony, the two agents “could either admit that they had done an inadequate job or suggest that Hill fabricated the new details expressly for the hearings.” They chose the latter course, signing sworn affidavits that Hill hadn’t specified Thomas’s lewd remarks in her interview.

Armed with the affidavits, Republican Senator Arlen Specter, then tasked with defending Thomas, asked, “When you made your statement to the FBI, why was it that that was omitted if it were so strong in your mind and such an odd incident?”

Of course, as Mayer and Abramson later uncovered, those details were in Brudney’s notes, proving that Hill’s story had been consistent all along. The two FBI agents had simply been less thorough than a Democratic staffer.

Further reading: Jeff Flake criticizes Kavanaugh’s “sharp and partisan” interactions on Thursday.

The Bush White House also took advantage of the FBI report to attack the credibility of Susan Hoerchner, whom Hill had told about her encounters with Thomas. The conservative pundit Bill Kristol, then–Vice President Dan Quayle’s chief of staff, discovered that Hoerchner had given the FBI an obviously incorrect date for a conversation with Hill, because of where Thomas was employed at the time. “On the witness stand, Hoerchner said repeatedly that she could not recall the exact date of the conversation and later explained that she had only given the FBI her ‘best guess,’” Abramson and Mayer explained. “But by the time the Republicans finished cross-examining her, Hoerchner had come across as a nervous and vague witness who failed to correct the impression that she herself had a history of concocting sexual harassment charges.”