I think the spirit of the introduction of the testimony system of investigators, is in order to prevent, it is possible, among other things, what happens to overturn sentence unfair of witness or defendant, the absurd result, to deal effectively with this. If you look at the relevant case law of the testimony system after the introduction of the investigators, the main material used to determine the presence or absence of special guarantees of trustworthiness associated with the testimony of investigators. If there is participants at the time, it is possible to mention his statement, a description of statement was created in the course of the investigation. Therefore, in order to be recognized innocuously the special guarantees of trustworthiness from the perspective of law enforcement, it or enlist a person or trusted counsel in the course of the investigation, to record the all process of investigation is most preferred and counsel or if the video recording research and participation of people with a trust relationship has not been made, and that along with the testimony itself of investigators, will be discussed in a comprehensive manner, such as the description of the written statement and assertion of the accused, the presence or absence of special guarantees of trustworthiness, it is necessary to judge. And, by notifying explicitly whether the certification of special guarantees of trustworthiness associated with the testimony of the investigator in the course of the trial, so as to additional proof activities for inspection, by this, the court, a sufficient psychological it is necessary while securing the article must determine the adoption of evidence.