The Horror Show (aka House III) (1989) | James Isaac

After viciously murdering over 110 people, the serial killer known as 'Meat Cleaver Max' Jenke (Brion James) gets the death penalty, sentenced to fry in the electric chair. Max doesn't go easily, staying alive for nearly ten minutes as they zap him with everything they have before expiring. However, something happens in the process of electrocution that allows Jenke to live on as a supernatural entity of electricity - one that seeks revenge on the cop that arrested him, Lucas McCarthy (Lance Henriksen). McCarthy suffers from PTSD, forced into a leave of absence while seeing a psychologist until well enough to return as a detective. However, despite seeing Jenke executed with his own eyes, McCarthy sees him everywhere - in his dreams, on his TV, and popping up whenever he's out and about. Either Jenke truly is a supernatural being taking up residence in McCarthy's furnace, or McCarthy's delusional and putting his family in grave danger.