The Ludwig Boltzmann Institute for Clinical-Forensic Imaging in Graz runs an outpatient center for victims of sexual or domestic abuse. In addition, the public prosecutors office occasionally assigns the Ludwig Boltzmann Institute to conduct forensic examinations and to subsequently issue an expert opinion in the framework of preliminary criminal investigations. This thesis shall illustrate the influence of these expert opinions on the outcome of the aforementioned investigations. Firstly, the different forms to terminate preliminary criminal investigations will be outlined from a procedural law perspective, followed by corresponding nationwide statistics by the prosecutors office. This is followed by an overview of the criminal offences where forensic examinations play a major role, namely violence or sex offences. Furthermore this thesis will provide an insight into the most important aspects of forensic examinations carried out by forensic doctors with a special focus on the forensic examination as defined in § 123 StPO. This is followed by the core of this thesis, namely a study illustrating the influence of forensic examinations on preliminary criminal investigations.