Classification of detective stories

Almost all whodunnit stories fall into one of the following story-o-types:

Setup: V is a victim who dies. D is the detective. X, Y, Z ... are the suspects. The killer K must satisfy K ϵ {X, Y , Z ...} U {D, φ, V}.

1. The least obvious suspect did it: This trick is used so often that it has become almost a cliche. Y is meek, good and helpful. Y seems the least likely to have carried out the murder. In the end though, Y is revealed to be the killer.

2. The most obvious suspect did it: As people read more and more novels which use trick #1, they start suspecting such unlikely characters. A clever writer reverses this by making the most obvious suspect the killer. The problem with this is if the reader hasn't come across trick #1 very often, the ending will fall rather flat.

3. The victim did it: No one suspects the victim, by virtue of the victim being dead. The ending reveals that the victim intentionally killed themselves, thus confounding everyone.Cards on the table is a good example of this trick.

4. Everyone did it: People instinctively expect only one of the suspects to be the killer. If more than one suspect were in collusion, the reader is much less likely to deduce the culprits. The most famous example of this is of course Murder on the Orient Express, where every suspect turns out to be the killer.

5. No one did it: There never was a murder: it was all an accident. Like trick #3, the reader feels a bit cheated since the perpetrator isn't brought to justice.

6. The victim is the victim: V is supposed to die, but W dies instead. The ending reveals that W was the intended victim after all. The ABC murders is a perfect example of it.

7. The fake victim did it: This takes trick #6 to one more level; not only is W the intended victim, the fake victim V is the killer. The Mirror crack'd from side to side is a good example of this.

8. The detective did it: This obviously doesn't work if the detective is famous. Also, for this to have a satifying ending, there has to be a second detective who reveals the killer. Bonus points if the story is being narrated from the detective's point-of-view in first person.

9. The butler did it: I just had to put that one there :D

10. Unexpected Motive: Given that the choice for 'who' is pretty limited, the motive is the factor writers get to play most with. Again, The Mirror crack'd from side to side is a brilliant example of a motive for which enough clues exist in the story, yet is very surprising in the end.

11. Unexpected Method: 'How' is the thing writers let their imagination run free over. The most interesting ones are the "impossible murders": murder which happened in a room which was locked from the inside etc.