This paper investigates sources of crime data mining, methodologies for knowledge discovery, by pointing out which forms knowledge discovery is suitable for which methodology. Furthermore, it identifies which data sources should be used for which knowledge discovery form in crime data mining. Similarities and differences between crime data mining methodologies show that some forms of knowledge discovery are suitable for particular crime data mining methodologies. It is offered that selecting the appropriate methodology depends on whether general or specific tasks required or high volume of crime data to be prepared.