When did efforts begin to professionalize the police in the West so they were more interested in solving crime, and what steps were taken say between 1850-1980?
Could you possibly enlarge on this with sources or some further comments?
I've studied policing in London and New York in the period 1830-1918, and while it would certainly be fair to say that detection rates for more complex crimes were, not surprisingly, below what they are today, that there was some suspicion (especially in London) of the appropriate role of a police detective, and that there was some corruption (significant in New York) that undoubtedly led to cover-ups in the cases of crimes committed by people with political connections, or linked to institutional corruption, I wouldn't go so far as to say these occurred "as a rule" across all types of case, or that the police were not interested in solving a significant proportion of crimes.
Are you interested in any particular type of case, or any particular location?