F.B.I. Girl (1951)

A governor planning to run for U.S. Senate has a secret past that could prove damaging to his political aspirations: he's a convicted murderer, and that will come to light if the FBI does an investigative check on him. He goes to a local crime boss for help. The racketeer arranges for a low-level FBI employee to take the incriminating file from FBI headquarters, but then she is conveniently murdered. Two FBI agents investigating her murder begin to think that something isn't quite kosher.