On TV show "Magnum, P.I.," who provided the voice for Robin Masters, Magnum's unseen employer?

During the TV series "Magnum, P.I." when it first aired in 1980 - 88, Orson Welles was the individual who provided the voiced of Robin Masters. After Welles died in real life, the writers on the show decided to have Thomas Magnum (Tom Selleck), a private investigator and Head of Security for Robin's Nest, start to suspect Jonathan Higgins of being the owner, Robin Masters. Higgins is the arrogant and self-assured estate manager for Robin Masters' beachfront estate on Oahu, HI. He is played by John Hillerman. There is great mystery surrounding Robin because his voice is only heard few times each year by other people on the show.

After Thomas tells his friends Theodore "T.C." Calvin and Orville "Rick" Wright that he thinks Higgins is Robin, the suspicion becomes a long running gag in the series. In the final episode of the series, Higgins tells Magnum that he really is his boss, Robin Masters. However, Higgins later recants at Rick's wedding. This causes a cliffhanger and 29 years later, still no one knows if Higgins is the mysterious and eccentric Robin Masters.