How Awful About Allan (1970)

After an eight-month stay in a mental hospital, a tormented man comes home to live with his sister; but a mysterious boarder may be trying to kill him.

Director:

 Curtis Harrington

Writers:

 Henry Farrell (teleplay), Henry Farrell (novel)

Stars:

 Anthony Perkins, Julie Harris, Joan Hackett - via IMDB 

https://archive.org/details/HowAwfulAboutAllan