The Astral Factor (1978)
Director: John Florea
Actors: Robert Foxworth, Stefanie Powers, Sue Lyon, Mark Slade, Marianna Hill, Elke Sommer, Leslie Pariah
Runtime: 85 min.
While studying the occult in jail, a convicted murderer learns to make himself invisible. He escapes from prison and uses his newfound skill to hunt down and strangle those who testified against him at his trial.