This paper is about criminal participation in a German case. The main aim is to know how psychological aiding works? For that, there is a brief description of criminal participation in general, including principal participation and aiding. After that, it is explained the background of the case. Also a detailed study of the Red Legion’s sentence is done. This case included psychological aiding issues, as well as co-perpetratorship issues. Finally, the main conclusion from the case is: the mere presence at the crime scene in the knowledge of a criminal offense is not enough to punish the agent as a psychological aider.