Although the central role of criminal investigators is to solve crimes that have occurred in the past, many current and future day-to-day problems confronting criminal investigators can be alleviated through more conscious investments in identifying and solving problems that are manifested in patterns. Problem-oriented policing has changed much regarding how police think about and do their work toward this end, but it has been applied primarily as a strategy for patrol operations. Some criminal investigation problems that lend themselves to this strategy are unique to particular settings, and some are common to criminal investigation generally. Specific areas of opportunity for substantial improvement in problem-oriented investigation include collaboration with patrol off icers, shift of focus from offenses to offenders and locations, and a more coherent use of modus operandi files and related data sources. This chapter explores the application of problem identification and problem-solving tools to these and other issues in criminal investigation.