Cozy Mystery Prologues
I suppose a literary agent or publisher would have the best advice on prologues, but here are my two cents. Write the prologue and then move on to the novel. If, at the end, you still need the prologue then consider keeping it. Maybe what you have is really chapter one? However, you may also find the essential details of your prologue have somehow found there way into the story. If so, 86 the prologue.
I agree with the concept of prologues coming into and going out of favor. I have seen both, sometimes in books within the same series. I do not use them. If it's essential information, I try to find a way to put it into the story, hopefully through action (showing not telling.)
On a practical level, I have been researching literary agents lately. They all request a brief query letter and either the first 10-20 pages or the first chapter. Here's the rub: if there is an essential element of my story in the prologue, possibly even the hook, how would the agent see it?
I'm not saying it can't be done, or done well; I am just not sure this is the era of the prologue. Best of luck on the book!
People advise against prologues because most new writers handle them so badly, and don't understand their function. If you're using it to show the crime and set the scene for the actual story, it's what mysteries often do.
But in the end the question is: does this prologue work for this story. And the only way I know to find that out is to post it and get reaction.