The Dead Don't Dream (1948)

Hoppy, California, and Lucky arrive at an inn for Lucky's wedding only to find it called off as Lucky's fiancee's uncle is missing. He is found murdered and on each of the next two nights a man is found missing the next morning. All three stayed in the same room and Hoppy has lots of suspects. That night he announces the murderer is right here among them and then takes that same room for the night hoping to flush out the murderer.