The Six key Elements Of Fictional Detective

1. The detective must be memorable
    ~Fictional detectives are stereotypically characterized as clever and a bit out of the ordinary. They set themselves apart from everybody else, with some extraordinary talent, habit, mannerism, interest or eccentricity. 

2. The crime must be significant
    ~Usually, the detective novel is constructed around a murder or a great mystery that the detective ( and the reader) must solve throughout the novel.

3.The criminal must be a worthy opponent
    ~In real life, most crimes are committed by ordinary, everyday, sometimes dull and stupid people. However in fictional detective novels the crimes are usually unrealistic for an everyday crime. Since the detective is extraordinary, then the crime must also be extraordinary.

4. All the suspects, including the criminal, must be presented early in the story
    ~The reader must be able to safely assume that the perpetrator of the crime is one of the main characters in the story, not someone whom the author is going to slip in one the unsuspecting reader in the next-to-the-last chapter.

5. All clues discovered by the detective must be made available to the reader.
    ~The reader must be given the same opportunity to solve the crime as the detective This means that the reader must be given the same evidence at the same time with the
character.

6. The solution must appear logical and obvious when the detective explains how the crime was solved. 
    ~In the end, the reader must see how all the evidence and clues fit together.