John from Retroslashers.net just posted a new article about Pitchfork Massacre. I recommend checking it out if you’d like to read his take on it: http://retroslashers.net/the-pitchfork-massacre-mystery-solved/
I did some further research and there was definitely no death scene shot for the couple in the basement as I previously speculated. The artwork in the Pitchfork Massacre ad is not from The Prowler. But I still think it’s still likely that a TV spot was shot to promote the film (Probably on video). Or at the very least a trailer cut together with Prowler footage. Will we ever find it? Probably not. The only chance would be: somebody happened to be taping local TV when the trailer was shown; that tape survived 30 years; and then somebody happens to view the tape, look up the movie and find one of these articles.
I’d say case closed… for now. But if you have anymore information, please don’t hesitate to contact me or RetroSlashers