From the inside cover:
While combating the forces of the mythos, investigators are often exposed to hideous horror and blasphemous secrets that drive them into the embrace of insanity. If they continue on their perilous path, the may eventually be defeated either through total insanity or death. In either case, they generate a large paper trail which others can follow. An admission form to a local sanitarium can spark an investigation into the life of a deceased inmate, and lead the seeker into realms of unearthly evil. This supplement is meant to aid the keeper in the creation of such clues for the investigator. Forms include a death certificate (good for any death that occurs in Massachusetts), a psychological profile, a police fingerprint form (for when the investigators run afoul of the law), and even a few singularly suggestive ink blots. These documents are all centered around Arkham Sanitarium and the related businesses and institutions in the small town of Arkham, Massachusetts.