The Trump administration's initial refusal to provide the complaint, as well as a string of media reports suggesting the complaint described wrongdoing by Trump in his posture toward Ukraine, ultimately led Speaker Nancy Pelosi to open an impeachment inquiry in late September. Within days of her decision, Maguire testified to Congress and the whistleblower complaint was released publicly. Trump also decided to release the readout of a July 25 call with Ukraine's president that became a central piece of evidence in the impeachment inquiry.

Schiff first asked the DNI for the whistleblower complaint after the agency's inspected general characterized it as an "urgent" and credible matter. Typically federal laws trigger a requirement that such complaints are forwarded to Congress. But in a Sept. 13 letter, Klitenic replied that rather than honor the inspector general's assessment, DNI consulted with the Justice Department, which overruled the inspector general and determined the complaint did not meet the threshold required to share it with lawmakers.

"Based on those consultations, we determined that the allegations did not fall within the statutory definition of an 'urgent concern' and that the statute did not require the complaint to be transmitted to the intelligence committees," Klitenic wrote on Sept. 13.

He also argued that the whistleblower had no legal right to approach Congress directly with his concerns. "We believe that it is important to apply the statute as it was written, because reading it to give a complainant a unilateral right to forward a complaint to the congressional intelligence committees would raise serious constitutional questions," Klitenic argued.

Klitenic's letter also hinted at Trump's role in the complaint, noting that it involved "confidential and potentially privileged communications by persons outside the Intelligence Community." Schiff said at the time that such a description could only apply to Trump or his top aides.

In a second letter, on Sept. 17, Klitenic rejected suggestions by Schiff and other Democrats that the whistleblower complaint had been improperly handled.

Klitenic's departure shrinks the pool of Senate-confirmed officials eligible to succeed Maguire as acting DNI, should his term expire without a permanent replacement. He was sworn in in August 2018.

Trump had previously nominated Rep. John Ratcliffe (R-Texas), a top ally and member of the House Intelligence Committee, as Maguire's permanent replacement. But he withdrew from consideration amid questions about his background.