William J. Caunitz 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 would eventually serve 30 years with the N.Y.P.D.

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.