Well, I've always thought that Roy was killed by the Gemini twins at Patty Testa's place after the Gambino's reached out to Gaspipe who set the thing up.

But one thing that had bugged me.....
The contract was first given to Gotti who couldnt get to Roy.
DeCicco couldnt get to Roy either so the Gambino;s reached out to Gaspipe.
Hmmmmm.............If I was Paul Castellano I would call in Nino Gaggi and say "you brought Roy into the family - YOU take him out".

I'm certain the twins killed him I just dont know if Nino was actually present or not!
But Richard Bullshitter Kuklinski certainly wasnt there - LOL