Complex sentence: Griffith continued to work in the film industry until his death, working as an assistant director at Monogram Pictures, an associate producer under Robert Sherwood, and as a director and then as an associate producer for Gregory Ratoff Productions.
Split into simpler sentences: Griffith continued to work in the film industry until his death. He was an associate producer under Robert Sherwood, and a director and then an associate producer for Gregory Ratoff Productions.