Expert witness
Expert witness is a person, who has not perceived the circumstances of the committed criminal offence with their own senses, but they are an expert in the specific field, on which they are to comment in relation to the criminal offence. Law enforcement authorities, i.e. the police, public prosecutor or court will ask for an expert opinion to be produced  to determine the investigated criminal activity provided they do not dispose of the required expertise in the specific field, e.g. in economics, in determining a price for an object, in health services, forensic medicine, psychiatry, ballistics, graphology and other fields. The expert passes a judgment on the particular circumstances of given case from a professional point of view.