Roland
Synopsis
A scientist working on advanced propulsion technology is killed by the handicapped janitor Roland, who then corrects the man's calculations. Mulder and Scully investigate and find that another recently deceased scientist who's head is cryogenically frozen, was Roland's twin brother and is controlling him telepathically from beyond the grave.
Again a pretty good episode, although it was fairly easy to conclude what was actually going on by the halfway point in the episode.
Superb performances by the actor/actress playing Roland and his girlfriend. I've no idea if they were acting or not, but great job either way.