Are police officers trained well enough on crime scene investigations?

I depends on what your definition of police is. In general and as agencies, police are well equipped and trained to conduct crime scene investigations. Usually a dedicated and specially trained unit is used for identifying and collecting criminal evidence (notably CSI units). Most police departments that don't have a dedicated CSI units utilize a detective division, trained beyond police basic training, to conduct comprehensive investigations usually in followup to generalized police actions by their agencies (but investigations may be self initiated). Some specialized law enforcement agencies have their field personnel conduct investigations from beginning to end (fish and game, casino control etc.). A lot of very small police departments either utilize their own officers as need be, or rely on larger agencies to conduct their investigations, such as the county sheriff, county police, state police or state detectives.Space