Oh, what a nice Christmas gift -- thank you, Mike. And call me Barbara.
No, I was never a cop; don't have what it takes to do that job. I just did the usual writer-ish thing of researching my subject. I read a lot about the structure of the NYPD and called some precinct houses with questions and had a nice long chat with the PR officer, Lt. O'Connell. Everyone was wonderfully helpful and explained things I couldn't figure out on my own (such as when Homicide is called in when someone dies in a fire and when it stays with the Arson Squad).
As to the departmental politics...well, sometimes I think all human activity is about the same thing: jockeying for position. You see it everywhere from government and big business all the way down to small groups of friends, so I knew it had to be rife in a huge police department like the NYPD. It's a common, shared conflict that I just put within the setting of police work.
And I'm sorry about "your" Captain DiFalco. Maybe he'll get his come-uppance one of these days.