Alibi for Murder (1936)

A radio commentator named Perry Travis fancies himself a brilliant amateur detective. The cops wish he’d stick to his microphone and let them do the detecting. This proves impossible when a famed scientist is murdered in Perry’s studio, right in the middle of the interview. All evidence points to Perry, and he sets out to clear his name before the Shadow-like villain roaming the hallways of the radio station gets away with murder.