Jacob Riis, the famous muckraking journalist and social reformer from the late 19th century, appears as a minor character in The Alienist. John Schuyler Moore, the story’s narrator, works as a police reporter who, like Riis, spends a good deal of time at New York City’s police headquarters on Mulberry Street. Moore, therefore, knows Riis well enough to call him “Jake.” As one of the novel’s supporting characters, Riis joins other real-life historical figures such as Paul Kelly, James T. “Biff” Ellison, Thomas Byrnes, Anthony Comstock, J. P. Morgan, and fellow muckraking journalist Lincoln (“Link”) Steffens.

There is irony in Riis’s fictional role as a character in the novel. On one hand, Riis has no significant influence on the story’s action. His appearances are few and brief. Moore refers to Riis for only two reasons: first, to point out that Riis was something of a bigot, and second, to lament Riis’s ostrich-like refusal to acknowledge the existence of the commercial sexual exploitation of children in the city. On the other hand, there is no question that Caleb Carr, while researching The Alienist, made extensive use of Riis’s How the Other Half Lives (1890), a landmark achievement in photojournalism that captured the squalor and degradation of the tenements in much the same way that Mathew Brady’s photographs first exposed the public to the horrors of the Civil War.