This research aimed to analyze the problem and the obstacle for the obstacle for the investigated and interrogated police officer, to compare the investigated and interrogated process among Thailand and the foreign countries and, and to propose the integration of the investigated and interrogated guidelines. This study utilized the qualitative research by using the in-depth interview based on the system theory with 70 key informants for analyzing the problem and the obstacle for the police officer’s case investigation and Interrogation. Used the documentary analysis for comparing the investigated and interrogated process between Thailand and the foreign countries, and used the focus group method for proposing the integration case investigation and Interrogation guidelines. The result found that the problems and the obstacles in the operation were insufficient resources, the police officer’s behavior, and the collaboration with the police officer. Comparing the investigated and interrogated process among Thailand and the foreign countries which were consisted of Socialist Republic of Vietnam, Republic of Korea, and Federal Republic of Germany found that the criminal proceedings in each countries were different depended on the country context. Proposing the integration of the investigated and interrogated can be found three guidelines. In conclusion, the proper investigated and interrogated process should focus on the integration in every process from starting to an end in order to be the most benefit for the case management and the people.