Monday Mystery - Rules to writing a mystery

The next few weeks I'll be giving you some information from the book Writing Mysteries. It's a handbook by Mystery Writers of America. It was given to me a couple years ago by a good friend who knew I was heading toward writing mysteries.

Today is about the 10 rules for writing a mystery.
1) Plot is EVERYTHING.
With a mystery the there is a problem in the beginning of the book  be it a murder, missing person or object, or the appearance of a person or object unknown to the cast of the story.  This problem must be resolved by the end of the book.
2) Your hero can be male or female and have an occupation inside or outside the law. But it is good to have a secondary character who is part of  law enforcement to keep things looking valid.
3) Choose a setting based on a combination of your needs and your familiarity.
4) Some violence is required whether it's the hero getting away from thugs or the one death that starts the inciting moment for the book.
5)There are some violence that is prohibited. graphic scenes of child abuse, rape, or cruelty to animals.
6)While most mysteries/detective stories are i first person narrative, use your discretion and write in either first person or third person depending on what you want your reader to know.
7)The hero cannot be the culprit and  the culprit cannot be the hero.
8) Play Fair. The culprit must appear early int eh book even though the reader doesn't know they are the culprit.
9)If you use more than two characters in a  scene make sure they all have a distinct voice.
10)  Authenticity is required.