William J. Caunitz (1933 — 1996) was a New York City Police Department officer who used his own experiences to write best-selling thrillers.
After serving in the United States Marine Corps, and working for an insurance company, he joined the NYPD in his twenties. He first worked as a patrolman, and eventually rose through the ranks to become a Lieutenant, followed by an assignment as a detective squad commander. Caunitz was praised for his "raw authenticity" when describing precinct day-to-day life in his novels, especially for One Police Plaza, which was eventually made into a television movie. His novels usually center around one or two police officers that follow detailed police procedures to solve a crime, and he also used some sensational elements of thrillers.
Caunitz died in 1996 from pulmonary fibrosis His last novel, Chains of Command, was half-completed at the time of his death and finished by Christopher Newman.