So I am currently writing an outline for a story that I am working on. It takes place in 1940s New York, the main character is a Police Homicide Detective. I just want to make sure I have everything historically accurate. Like if the ranks are the same as they where then. In movies you always see the generic chief that runs a precinct. But it is my under standing that the Chief of Police/Commissioner is in charge of the department as a whole. I have done a little research but I am having trouble figuring out what he person in charge of a precinct is called. I have seen Deputy Inspector, but is that who is the head of a precinct? Thanks in advance for the help.

Are detectives even a part of a precinct? Or are they a part of a specific department dealing with specific crimes? Like a Homicide Department. Are NYPD Detectives restricted to a certain area or jurisdiction or do they just go where they are needed?