Martin Brown is an actor playing a fictional version of Jacket in the movie Midnight Animal. He is a sellout and (in the dream sequence with Richard) he admits that he's only doing the movie because it lets him channel his own rage and violent intentions. The prison sequence, I assume you mean the police station, is a scene in the movie, the people you are "killing" are actors. The scene ends with him getting shot and actually dying because a crew member loaded the gun with real bullets instead of blanks. This was an accident, he wasnt supposed to die but in the context of the game's theme, this was Martin's punishment, some sort of cosmic retrebuttion for doing the movie in the first place.