The article is devoted to the topical issue of using special knowledge of experts and specialists in the course of the judicial investigation in murder cases. The necessity of using special knowledge in court arises in situations when in preliminary investigation the issues requiring special knowledge and important for identifying the facts of the case that can influence the sentence in murder cases have not been clarified, or the experts (specialists) have not given definite answers to the questions posed. Special knowledge is required in murder cases when forensic investigation of experts is commissioned at the interlocutory motion of the parties. The article discusses the situations when forensic investigation is commissioned, the types of expert examination most often conducted during the judicial investigation in criminal murder cases. It examines the use of the polygraph in judicial investigation of murder cases, in particular the appointment and performance of polygraph psychophysiological examination and its results in determining the facts to be proved in the case.