From the introduction:
The idea of bringing back the souls of the dead to serve as witnesses in their own murder trials has been around for as long as people have claimed the ability to talk to the dead, but juries (not to mention the legal code) have always been reluctant to accept the testimony of mediums. After all, there’s really no way to distinguish between a genuine channeler of the dead and a good actor lying in order to influence the trial. Dr. Osiris Shade attempted to increase the credibility of the dead by placing their bodies into various sorts of mechanical constructs, but there was still a question as to whether the golem’s words were really those of the dead person or simply part of an elaborate hoax. When Shade found a way to place the recovered souls into the bodies of the recently deceased, things started to change.