The enactment of Law Number 20 of 2025 concerning the Criminal Procedure Code (KUHAP) introduces fundamental changes to Indonesia’s criminal justice system, particularly concerning investigators’ authority, the mechanisms for coercive measures, strengthened coordination between investigators and public prosecutors, and the protection of suspects’ rights. These changes affect the investigation of narcotics crimes, which are characterized by organized structures, cross-regional operations, and the use of technology. This study aims to analyze the role of Indonesian National Police investigators at the Narcotics Investigation Directorate of the West Nusa Tenggara Regional Police in handling narcotics crimes under the new Criminal Procedure Code. The study employs a socio-legal (empirical juridical) method using statutory, conceptual, and empirical approaches. Primary data were obtained through interviews, observations, and documentation and were analyzed descriptively and qualitatively by connecting legal norms with their implementation in practice through Role Theory and Integrated Criminal Justice System Theory. The findings show that investigators perform their role through the stages of receiving reports, preliminary investigation, formal investigation, evidence collection, implementation of coercive measures, suspect determination, case-file completion, and coordination with public prosecutors, the National Narcotics Agency, forensic laboratories, and other relevant institutions. In principle, these roles are consistent with the normative provisions of the new Criminal Procedure Code. Nevertheless, gaps remain between role expectations and role performance, particularly in the uniform understanding of the new rules, digital evidence management, electronic administration, and documentation of interinstitutional coordination. Strengthening technical guidelines, improving human-resource capacity, and optimizing interinstitutional coordination are therefore necessary to support the effectiveness of an integrated criminal justice system.