Murder by Natural Causes (1979)

"Murder by Natural Causes" is a 1979 Mystery movie directed by Robert Day and starring by Hal Holbrook, Katharine Ross. An elaborate mystery involving a famous mentalist, his unfaithful wife who is trying to literally scare him to death, the best friend of the family, and the wife's ham-actor lover -- not only an intriguing who- (or whether) dunit, but also a literate, adult dramatic puzzle with an endless series of twists.