The article considers the diagnostic essence of polygraph testing. It analyzes and compares the views of scholars on identification of the subject and questions of judicial psychological examination. It considers the definition of the questions and subject of polygraph psychological procedure given in earlier research. It is shown that polygraph testing is aimed at diagnostics of awareness of patients about the details of the investigated event. It is proved that judicial psycho physiological polygraph procedure in its essence, objectives and area studied, as well as its methods represents a new kind of judicial psychological examination i. e. examination of the person awareness of the investigated event. The authors define the notion of “the person’s awareness of the investigated event”. They specify the subject, questions, methods, and limits of competence of the judicial psychological examination of the person awareness of the investigated event. They also suggest formulation of questions to the polygraph examiner studying the awareness of the person of the investigated event.