It is possible that with him was buried and secret Mueller. As evidenced by Sergo Beria, son and homemade "trustee" Lavrenty Pavlovich, his father did not register the general procedure of some of the most valuable of its agents. For example, prominent foreign politicians, diplomats, public figures. That is, these people, information on the work which the Soviet Union in case of a leak would cause a negative international response, and other unwanted effects. Beria took into account that such leakage can not be completely excluded with any degree of secrecy - the information can leak through defectors to the West, "doubles", the recruitment of staff of the MGB. Therefore, these "special" private affairs were not got all the agents. And of them only knew Beria himself and several people to communicate directly with them. Individuals who could certainly hold his tongue. Mueller on all items well suited for the said category of agents. This means that even the KGB archives vsverhsekretnyh information about it can not be.