The prosecutor is a native of Sarpeidon, one of many who escaped the destruction of that planet when its sun went supernova. He lived out the remainder of his life in the past, during a period when men and women were tried for witchcraft, on the basis of superstition. While his position was secure as a prosecutor, he lived in some trepidation that the locals would become suspicious if he accidentally let slip too much knowledge of the future - they might accuse him of second sight and put him to death! The day that his fear was greatest was the day that a man wearing strange clothes (strange for Sarpeidon in any era) appeared and was accused of witchcraft by a woman he saved from robbery. This man (James T. Kirk) spoke of the library, which was the center of operations for the mass time-travel project. The prosecutor feared for his life, and fled this strange madman, leaving him to his own devices in self-preservation.