Corrected entry: Roy's motive behind his killing spree is that he's upset his son, Joey, was murdered by Vic. So why kill everyone else, except the person that was solely responsible?
Bishop73
14th Jul 2018
Friday the 13th Part V: A New Beginning (1985)
Correction: He could also blame everyone else for not stopping it and letting his son die.
Correction: Roy also loses his mind and snaps. He simply blames everyone for his son's death, not just Victor. He's crazy and goes on a killing spree (just like Pamela Voorhees did). There's no plot hole when a crazy person doesn't act rationally. Plus, Victor was locked up and Roy might not have been able to get to him.
Bishop73