From the form of your question, it seems you need some background materials with a theoretical perspective for this purpose. Here are some sources to examine:
Knight, Stephen. 1980. Form and ideology in crime fiction. Springer.
Priestman, Martin, ed. 2003. The Cambridge companion to crime fiction. Cambridge University Press.
The related issue is identifying a list of books that become the materials for the analysis. Since crime fiction exists in different contexts -- that is, in different periods of historical time, and in different countries -- you have to begin with a frame for selecting works of fiction which makes sense. For example, if you were studying crime fiction in Country A, and County A has a very long history of that type of literature -- say 150 years worth -- it might NOT make sense to include very old works along with very new works UNLESS you wanted to study how the image of crime in fictional works changed over time.