Rudy Giuliani 'may have been compromised' by the Kremlin, and FBI leaders didn't care, alleges special agent Johnathan Buma

Johnathan Buma says his FBI supervisors didn't care about his leads tying Giuliani to Russian intelligence.

Buma's disclosures to the Senate raise questions about Giuliani and the origins of the Hunter Biden-Burisma story.

The FBI is gradually emerging as the ultimate referee in US politics.

Whistleblower Buma says he was stymied by FBI efforts to investigate Rudy Giuliani .

Buma alleges that the FBI retaliated against him, and that he was transferred from his human intelligence squad to a less desirable assignment doing surveillance.

Viewers of GOP 's congressional hearings "aren't getting the full story," Buma said.