Episode 36 aired February 22, 1948 over the CBS Radio Network. A professor who has rejected companionship is haunted by an invisible creature. Luis Van Rooten as Professor Guildea and the narrator, Father Murchison played by Parley Edward Baer (PHOTO) (August 5, 1914 – November 22, 2002) who was an American actor in radio and later in television and film. Despite dozens of appearances in television series and theatrical films, he remains best known as the original "Chester" in the radio version of Gunsmoke, and as the Mayor of Mayberry (Roy Stoner) in The Andy Griffith Show.

https://en.wikipedia.org/wiki/Parley_Baer