In the late 70s or so, (I was 6ish)
There was a movie with a Jamaican man in a prison cell lit with bluish light. He used a broken piece of glass to cut a mans throat. Then the scene turned into some sort of psychodelic scene with predator like heat vision type of imagery.
This is all I know.
I'll search the "penatentary" series to see if that's it.
Hmm.. maybe try THE HARDER THEY COME.