The more featureless and commonplace a crime is, the more difficult it is to bring it home.
The stage lost a fine actor, even as science lost an acute reasoner, when [Holmes] became a specialist in crime.
Ex-Professor Moriarty of mathematical celebrity... is the Napoleon of crime, Watson.
The larger crimes are apt to be the simpler, for the bigger the crime, the more obvious, as a rule, is the motive.
Crime is common. Logic is rare. Therefore it is upon the logic rather than upon the crime that you should dwell.
The most difficult crime to track is the one which is purposeless.