Washington (CNN)A former investigator with the House Select Committee on Benghazi is accusing the Republican-led panel of carrying out a politically motivated investigation targeting former Secretary of State Hillary Clinton instead of the thorough and objective fact-finding mission it was set up to pursue.

Major Bradley Podliska, an intelligence officer in the Air Force Reserve who describes himself as a conservative Republican, told CNN that the committee trained its sights almost exclusively on Clinton after the revelation last March that she used a private email server during her tenure as secretary of state. That new focus flipped a broad-based probe of the attack on the U.S. consulate in Benghazi on September 11, 2012, into what Podliska described as "a partisan investigation."

Podliska, who was fired after nearly 10 months as an investigator for the Republican majority, is now preparing to file a lawsuit against the select committee next month, alleging that he lost his job in part because he resisted pressure to focus his investigative efforts solely on the State Department and Clinton's role surrounding the Benghazi attack. He also alleges he was fired because he took leave from the committee to fulfill his military service obligations, which would be an unlawful firing.

"I knew that we needed to get to the truth to the victims' families. And the victims' families, they deserve the truth -- whether or not Hillary Clinton was involved, whether or not other individuals were involved," he told CNN in an exclusive TV interview that will air Sunday on "State of the Union." "The victims' families are not going to get the truth and that's the most unfortunate thing about this."