Dead and Buried
(1981)

A small town sheriff (James Farentino) discovers that a local undertaker has been resurrecting the dead. Most of the local inhabitants are now undead, and have, at the undertaker's orders, been killing tourists who then join the ranks of the towns undead. The secret surprise twist is that the sheriff's wife (Melody Anderson) is in fact one of the undead. The second rather stupider twist is that the sheriff is apparently undead too, and didn't know it. He goes insane when he finds out.

Thanks Chris H!

(Links open in new window)
Read more about this film at The Internet Movie Database.