1. The detective must be memorable.
Clever
Out of the ordinary
Have a habit, interest or talent

2. The crime must be significant.
usually a murder or a great theft
a crime that can not be reversed or made amends for
worth detectives time and effort

3. The criminal must be a worthy opponent.
Intellectual
Skillful
Clever
A battle of intellects between the detective and the criminal.

4. All the suspects, including the criminal, must be presented early in the story.
a mental contest exists between the reader and the detective.
a “fair play” rule

5. All the clues discovered by the detective must be made available to the reader.
All evidence presented to reader and detective alike
Also a “fair play” rule

6. The solution must appear logical and obvious when the detective explains how the crime was solved.
All the information must fit together like a jigsaw puzzle.