In the diploma paper criminal investigation and enquiry as part of a preliminary procedure is analyzed, their role in criminal procedure, and interactions between persons who are being part of mentioned parts of criminal procedure. Special attention is focused on protection of accused person and his rights in preliminary procedings of criminal procedure, and judicial control of enquiry and prosecutorial functions that state atturney has.Comparison method are used in this paper to show the differences between previous regulations of preliminary procedure, and the amended version of preliminary procedure which is compatible with all important principles, guaranteeing that person who is prosecuted will have minimal rights that will allow him to defend himself from criminal accustaions on efficient way. State atturney has a central role in preliminary procedure, as he is controling and managing with investigation and enquiry. The main tasks and responsibilites in criminal prosecution of state atturney have been analyzed in this paper. Beside state atturney, court of law has a very important role in criminal procedure as a warrant of legality of investigation and enquiry. Independence of judiciary reestabliches balance between state atturney and defendant, when that balance is disrupted.