The investigating officers must make important decisions, such as reviewing various suspects, the thoroughness of interrogations, and prioritizing different investigative approaches. The guide helps reduce uncertainties on-site and makes interrogations and credibility assessments transparent in their basic structure. The authors provide concrete suggestions, supplemented by exercises. The guide follows the ideal typical course of an interrogation. It becomes clear why open questions, free narratives, and a detailed protocol are important. The authors outline the goals, structure, and process of interrogations. They provide insights into tactical approaches and instructions. They emphasize the systematic search for alternative hypotheses as opposed to simply assuming the truth of statements.