Criminal offenses have become part of our daily lives, whether it be traffic accidents, blood cri-mes or something else. To resolve them successfully, it is of great importance to conduct quality investigations and evidentiary actions , which are used to collect evidence of the factual situation from the scene. The Thesis presents the manner of work of the authorities from the moment of learning about the commission of a criminal offense, starting with the investigation through the conduct of evidentiary actions and finally the reconstruction. The actions of the authorities in cases of urgency of evidentiary actions have been studied in more detail, when the authorities must act as soon as possible due to the danger of delay. The focus of the thesis is on the evidentiary work of the investigation and reconstruction, as a supplement to it. The importance of the plan of actions and their implementation methods is pre-sented, as any initial omission cannot be compensated for later. The goal is, with special techniques and means and an expert investigation team, to gather as much evidence as possible on the basis of which, the reconstruction can be carried out as close as possible to the original event. Timely and quality securing of the scene in its original form, plays an important role in the further course of the procedure. The more precisely the investigation is performed, the more credibly the reconstruction will bring us closer to a specific event. Nowadays, modern computer technology has developed, which enables faster and more precise "revival" of the scene, which ultimately facilitates the acquittal or conviction.