FBI Director Christopher A. Wray at an event at the Heritage Foundation in D.C. on Oct. 13. (Chip Somodevilla/Getty Images)

A trio of House conservatives, who have succeeded in getting the Judiciary Committee to keep questioning the FBI’s 2015-2016 probe of Hillary Clinton’s private email server, have sent a letter to the bureau asking for more answers before Director Christopher A. Wray next testifies.

The letter grew out of emails from October 2016, first released this month after requests by the conservative group Judicial Watch, in which FBI deputy director Andrew McCabe said that the email probe was “referred to as ‘special,’” which limited his access to it. That email grew out of yet another round of Clinton questions — a controversy, in the weeks before the election, about whether McCabe should have recused himself because Gov. Terry McAuliffe (D-Va.), a Clinton ally, helped McCabe’s wife raise money for a state senate race.

In the letter, Reps. Matt Gaetz (R-Fla.), Andy Biggs (R-Ariz.) and Louie Gohmert (R-Tex.) demanded answers from Wray about what the “special” designation meant.

“Who decided that the investigation would be handled ‘at HQ with a small team’ rather than by the Washington field office?” they asked. “What processes are in place at the FBI to ensure that ‘special’ treatment is not given to other political figures?”

Since Judicial Watch released those documents, some analysts have argued that “special,” in FBI lingo, did not mean the bureau was treating Clinton with kid gloves. “The term ‘special’ is a relic from the Hoover era (1924-1972),” wrote retired FBI agent James Gagliano in the Hill. “I have canvassed a number of retired agents and all associated it with a case classification. The designation of ‘special’ has also been known to have been used interchangeably with the designation ‘major case.’”

In an interview, Gaetz argued that the new emails nonetheless raised questions that had not been settled by the 2016 election, about how Clinton was able to evade real legal penalties for her use of the private server. The “special” email, he said, was the latest reason to ask whether some people in the government were determined to protect political elites.

“I had no idea how far the iceberg went under the water line,” he said.

In the letter, Gaetz and his colleagues also ask Wray to explain whether the work of Fusion GPS, which paid for a dossier of research from former intelligence agent Christopher Steele, was paid for by the FBI or used to justify wiretaps of the Trump campaign and the Trump transition.