Complex investigations in the Soviet Union are becoming popular, but they lack a theoretical basis. Most investigations, which include only forensic medical expertise, are conducted in the office of forensic medicine, and complex investigations by a team of forensic medical and criminal experts (which are conducted within the Ministry of Justice) are still rare. Furthermore, forensic medical investigations are inadequate and limited to a search for elementary clues. Even in the cases when both forensic medical and criminal experts cooperate, not all the latest developments in criminal expertise are used, and persons with expertise in matters pertaining to an investigation are rarely consulted. On the other hand, there are instances when a team of experts is unnecessary in that forensic medical expertise would suffice. To avoid these problems, uniform guidelines for conducting complex forensic medical and criminal investigations should be established by both the Ministry of Justice and the Ministry of Health and published in the form of an interdepartmental document. The guidelines should specify which investigations should be conducted by the office of forensic medicine and which by the team of medical and criminal experts, as well as what constitutes adequate qualifications. Furthermore, special courses prepared by both Ministries should be conducted for forensic medical experts on criminal expertise and for criminal experts on forensic medicine. Sample cases are included.