(written from a Production point of view)
Ingalls knew Star Trek creator Gene Roddenberry from their days as officers of the Los Angeles Police Department in the early 1950s. The following decade, Ingalls wrote two episodes for Roddenberry's Star Trek: The Original Series, the first being the first season's "The Alternative Factor". This was followed in the second season by "A Private Little War", for which he chose to be credited under the pseudonym Jud Crucis. He substituted this name after Roddenberry rewrote the episode, removing many of his overt Vietnam parallels. Jud Crucis was Ingalls' wordplay on "J[esus] Crucified."(citation needed • edit)
Besides Star Trek, Ingalls also wrote for Have Gun - Will Travel (another series Roddenberry wrote for), Bonanza, The Virginian, Adam-12, and Fantasy Island. The latter series starred Ricardo Montalban, who played Khan Noonien Singh. Ingalls was also a producer for Fantasy Island and also directed for the series. Ingalls also served as producer on Have Gun - Will Travel, The Virginian, and the fifth season of T.J. Hooker, starring TOS star William Shatner, as well as James Darren and Richard Herd.
One of the episodes he wrote for The Virginian – which aired in January 1963 – guest-starred future TOS actor DeForest Kelley and future DS9 guest star Brian Keith. This episode was later edited together with another episode to produce the 1971 TV special The Bull of the West.
In addition to his episode television work, Ingalls also wrote the screenplay for the 1974 film Airport 1975 and co-wrote the TV movies The Initiation of Sarah (1978) and Captain America (1979), among others. He later retired from show business, but not from writing: in 2005, he published a book titled The Watchers on the Mountain, a work of fiction about the Navaho Indians.