Lean Six Sigma (LSS) continues to greatly interest public sector organizations as a means to continuously improve service performance. However, given the plethora of research and literature on LSS in the public sector, research specifically about LSS in policing and prosecution services, which are dominated by knowledge work, is significantly limited. It is necessary to measure the knowledge work performance, to achieve continuous improvement. This manuscript presents a case study about the use of LSS in the Norwegian police service. It reports on the existing framework of LSS and explicates how to systematically analyse data regarding knowledge work-related waste to identify improvement areas in the criminal justice process. The LSS methodology and framework applied in this study provides a systemic approach that uncovers waste, which gives grounds to holistically analyse and indicate how the current overall process is performing, based on the scope of defects. This study demonstrates the implementation potential of LSS in policing and prosecution services to support managers who are engaged in any form of continuous improvement initiatives. The findings also add evidence to the existing argument on the applicability of LSS in policing services. However, there is a need to further develop and apply the LSS methodology in such a context.