In Lethal White, we are introduced to Mitch Patterson, a private investigator who has twice worked opposing sides to Strike’s clients in divorce proceedings. He is physically described as being “tall and broad” with “thick silver hair” and a “squashed, deeply pitted face.” Personality-wise, he is described as “unpleasant” by Eric Wardle. Patterson is a former senior officer in the Metropolitan Police. Wardle tells Strike that Patterson “got results” and implied that he has used violence in the past in order to do so. This alleged violence might be what led to Patterson’s “early retirement” from the Met.

Hired by an unknown person, Patterson has been making things difficult for Strike and Robin. He confronts Robin outside the House of Commons one morning and appears at her house on Albury Street another day in an attempt to speak with her. Strike also spots him on Denmark Street one morning and is insulted that Patterson appears to think Strike won’t notice him lurking in a doorway in jeans and a hoodie. 

While trying to determine what Patterson is up to, Strike considers that Patterson might have been hired by the press or a person Strike is currently investigating. Strike’s biggest concern is that Patterson’s client is Jago Ross, the husband of his former girlfriend, Charlotte.

In The Ink Black Heart, Robin recommends Patterson Inc to Edie Ledwell as a firm that does cyber-investigation (Ch 7). Strike has managed to poach a subcontractor, Dev Shah, from Patterson Inc (Ch 2). Shah later tells Strike that Patterson “had a sideline in using his agency to fuck over people he had person grudges against” (Ch 27).