Trivia

For many years, he was married to Academy Award-winning actress Mercedes McCambridge, whom he had met while producing and directing Orson Welles' 'Mercury Theater' summer series in 1946. Markle subsequently directed McCambridge in starring roles on his Studio One and Ford Theater radio series.

Adopted Mercedes McCambridge's son, John Lawrence, from her first marriage to writer William Fifield.

Before he became a television and film director, he was the producer, director, and occasional star of the CBS radio dramatic anthology series 'Studio One', which later became a hit television series. The radio version of 'Studio One', which was sustained by CBS, later became radio's 'Ford Theatre', when a sponsor for the series was found. 'Ford Theatre' used the same hour-long format of adaptations of plays, novels, and sometimes films that Markle had used on the Studio One program.