Problem setting. The article considers features of the interaction between an investigator as a representative of the prosecution and other various participants of criminal proceedings including a head of investigation unit, prosecutor, investigative judge and others. The topicality of raised questions in the current article is confirmed by the fact that previously the interaction between an investigator and other participants of criminal proceedings in pre-trial investigation was conducted in terms of the former Criminal Procedural Code of Ukraine (1960). Recent research and publications analysis. Some of questions regarding the interaction between an investigator and other participants of criminal proceedings in pre-trial investigation were examined by Linovskii V. A, Bandurka A. M., Groshevii Y. M., Larin O. M., Loboika L. M., Pogoretskii M. A., Tatarov O. Y., Sheiffer S. A., Golovko L. V., Baulin O. V., Zelenetskii V. S., Yukhno A. A. and others. Paper objective. The main aim of the article is a research of features of the interaction in current circumstances between an investigator and other participants of criminal proceedings including the head of investigation unit. It concerns as well the research of different scientific views regarding the matter and various ideas about improvement of principal norms in the Criminal Procedural Code of Ukraine and other legal acts that regulate the above-mentioned interaction. Paper main body. During the pre-trial investigation the essential question is the interaction between an investigator and a prosecutor who conducts an oversight in criminal proceedings. The current Criminal Procedural Code of Ukraine greatly expanded the full powers of the prosecutor to oversee the compliance of laws during a pre-trial investigation. Only the prosecutor should conduct a procedural supervision in a pre-trial investigation. We believe this procedural possibility limits an investigation independency. The interaction between an investigator and court during the pre-trial investigation reflects in judicial control over the investigation activity. An investigative judge takes almost all essential decisions in the pre-trial investigation. We believe such procedural and judicial control during the pre-trial investigation is excessive, and legally, undercover investigative (detective) actions could be controlled by the prosecutor. It has been always discussed the question of the interaction between an investigator and various detective units. The matter is still unsolved. We believe consideration should be given either to allow detectives to conduct independently undercover investigative (detective) actions or request their conducting to an investigative judge or prosecutor. Conclusions. Besides that, consideration should also be given to research the interaction between an investigator and an expert (specialist). We believe that the criminal responsibility for providing false statement and an intentional obstruction of identifying the truth in criminal proceedings should also be reflected in the Criminal Procedural Code of Ukraine.