Earliest episode not adapted from a novel or short story by Erle Stanley Gardner. Before it was a TV show, "Perry Mason" was a radio program. This entry was adapted from a 2-part radio episode that aired in January 1951.
This episode introduced the term "schizophrenia" to the audience in place of "dual personality." Today this condition is known as "dissociative identity disorder."
Aired approximately seven months after the release of The Three Faces of Eve (1957), which was based on a true story about a woman with multiple personality disorder.