As a result of the scandalous child homicide in Győr (year 2019), which case got a high publicity in the media, we decided to deal with the following question: what reasons could lie behind such homicides. We studied the criminal psychology of homicide and also tried to observe the connecting psychology-related questions. As a result of our study, we identified that the common specialty of criminal personality disorder and criminal endangerment is the general immaturity of personality (as a result of obstruction in personality development and harm of personality) and the high intensity of aggressive behaviour whose deduction is rejected by the society. On the top of the foregoing comes the moral defect of the perpetrator, which means the lack or severe distortion of moral rules governing his or her behaviour.