Most readers of mystery and detective fiction are familiar with the Whodunit concept. A crime is committed and we the reader are given the task of deciphering WHO it was. A tried and true formula for many happy hours of reading.
Some of my personal favorites have been Whydunits.
The author shares the crime with the reader from the start and we follow the psychology of the protagonist as to why he/she committed the crime (the back story) as well as the procedures that the law enforcement agencies utilize to catch the criminal.
Some excellent examples of Whydunits are:
"A judgement in stone" by Ruth Rendell
"Clean cut" by Theresa Monsour
The movie "Fracture" starring Anthony Hopkins and Ryan Gosling is an example of a Whydunit on film. The watcher knows who committed the crime, but is compelled to see if the police and lawyers can prove his guilt in the face of his genius.
Please share your favorite titles whether they be Whodunits or Whydunits.