Washington (CNN) Christopher Sharpley, the acting Inspector General of the Central Intelligence Agency, is withdrawing his nomination after former colleagues alleged he retaliated against them for blowing the whistle on CIA IG officials' alleged mishandling of evidence.

According to two sources familiar with the matter, and confirmed by the CIA, Sharpley sent an email to staff on Wednesday telling them he was pulling back his nomination to be CIA Inspector General and would be retiring from CIA within 30 days to seek other opportunities. His specific reason for withdrawing now was not immediately clear.

His resignation comes as President Donald Trump continues to face difficulties installing his candidates in key roles -- and as the intelligence community comes under increased pressure from the White House surrounding the various investigations into Russian meddling during the 2016 US presidential elections.

Sharpley, the former deputy Inspector General under President Barack Obama, has served in watchdog offices across government for decades after he left the Air Force. He has served in the acting role since 2015.

Sharpley has been the subject of complaints made by multiple former employees within the Inspector General's Office. Andrew Bakaj and Jonathan Kaplan, two of the retired officials whose complaints are now public, alleged that Sharpley punished them for reporting wrongdoing within the office. There are additional complaints from employees who have not revealed their names.

Read More