During his assignment to hunt down the elusive sixth replicant, Rick Deckard was taken to the Van Nuys Pet Hospital, where he spoke to Isidore. Isidore condemned Deckard's job as a Blade Runner, likening it to that of a Rassenprüfer of the Third Reich. He further stated to Deckard that the Voigt-Kampff test had caused the deaths of actual humans – citing the St. Paul incident – and ensured him that there were replicants Isidore himself serviced that could pass the empathy test. Isidore assured the Blade Runner that he would be very surprised to learn what humans were actually replicants.
With this, he revealed to Deckard that Pris – a replicant he had retired – was actually a human who had convinced herself that she was a replicant.