Dr. Hervey Cleckley, in the 1890s, described a psychopath as a complex construct resembling human personality with remarkable accuracy. This depiction highlights that a psychopath can imitate the behavior and characteristics of a typical individual so convincingly that even close examination does not reveal their true nature. Their ability to blend in makes it difficult for professionals to distinguish between them and genuine individuals.

In Erik Larson's "The Devil in the White City," this characterization of psychopaths underscores the chilling nature of such individuals. Cleckley's assertion that their mimicry is so perfect blurs the lines between authentic human experience and cold imitation, suggesting a deeper understanding of the disturbing capabilities inherent in psychopathy. The exploration of this concept contributes to the broader narrative of manipulation and deceit central to the book.