13 December 1946 MEMORANDUM FOR MAJOR-GENERAL A. N. VASILYEV Subject: Bacteriological Warfare Several members of our staff, including Justice A. J. Mansfield who is chargeable with the duty of presenting evidence relating to Class “B” and “C” offenses, have given careful consideration to the statements of Major Karazawa and Major-General Kawashima regarding the activities of the Ishii Detachment in experimenting with bacteria as a means of attack. Upon directing investigation of Japanese records and reports on the subject of bacteriological warfare, I learned that an experienced investigator was sent directly from the United States to Japan where he conducted a seven-week investigation of this detachment, and no evidence was brought to light which would indicate that these experiments were being made at the direction of the General Staff in Tokyo or that any reports have been received relating to these experiments. The Tribunal has made it very clear as to the evidence relating to atrocities and prisoners of war, that such evidence will not be received in the absence of an assurance by the Prosecution that the accused of some of them could be associated with the acts charged. We do not consider that the evidence now available is sufficient to justify an assurance that any of the accused can be associated with this activity by any of the criteria adopted by the Court with reference to atrocities and prisoner of war offenses. Although our investigation will continue for the purpose of obtaining additional evidence, the chance of success in the light of the investigation already made is so slight that it is not considered wise or reasonable to request the U.S.S.R. to produce the witnesses under these circumstances. ______________ Frank S. Tavenner, Jr.