Doppelganger

Biosoft. Organic programming that hijacks the victims' minds, turning them into anything from a docile plaything to an emotionless assassin. Paul Coulter is an expert in detecting Doppelgangers, and was the closest agent to tracking their source. In a world of Megacorporations and intrigue, the stakes are death or virtual immortality. Can he be persuaded to continue an investigation that almost killed him?  This science fiction mystery novelette originally appeared in Leading Edge magazine.