The solution of felonies is possible only with the combination of investigating criminal cases and operative search activity of the appropriate bodies which is exercised by secret invasion into private lives of citizens and violation of their constitutional rights. That is why it is necessary to guarantee the lawfulness of such invasion which is provided with legal proceedings and prosecutor’s supervision and also with the institution of the reasons for the lawfulness of the invasion determined by the Federal Law «On Operative Investigation Activity». The prosecutor’s has the powers which are realized in the forms of supervision depending on the body whose activity is supervised. The prosecutor must ensure the observance of defending guarantees of the persons participating in the secret work according to the given law. The reasons for implementing the verifications are appeals of citizens, officials, juridical persons, materials of criminal cases, lack of unsolved crimes and non-execution of commissions of the competent organs.