Shirō Ishii Biography . Early years . Ishii was born in the former Shibayama Village of Sanbu District in Chiba Prefecture , and studied medicine at Kyoto Imperial University . He was commissioned into the Imperial Japanese Army in 1921 as an army surgeon , second class ( surgeon lieutenant ) . In 1922 was assigned to the 1st Army Hospital and Army Medical School in Tokyo . There his work impressed his superiors enough to gain him , two years later , post - graduate medical schooling back at the Kyoto Imperial University . In 1925 , Ishii was promoted to army surgeon , first class ( surgeon captain ) . Beginning in 1928 , he took a two - year tour of the West . In his travels , he did extensive research on the effects of biological warfare and chemical warfare developments from World War I onwards . It was a highly successful mission and helped win him the patronage of Sadao Araki , Minister of the Army . He received promotion to senior army surgeon , third class ( surgeon major ) , in January 1931 . Biological warfare project . In 1932 , he began his preliminary experiments in biological warfare as a secret project for the Japanese military at Zhongma Fortress . He was promoted to senior army surgeon , second class ( surgeon lieutenant - colonel ) in 1935 . In 1936 , Unit 731 was formed . Ishii built a huge compound – more than 150 buildings over six square kilometers – outside the city of Harbin , China . The research was secret , and the cover story was that Unit 731 was engaged in water - purification work . Ishii was promoted to senior army surgeon , first class ( surgeon colonel ) in 1938 . On 9 February 1939 , he gave a lecture on bacteriological warfare in the War Ministry Grand Conference Hall in Tokyo . One of the attendees was prince Yasuhito Chichibu , Hirohito ' s ( the 124th Emperor of Japan ) brother , who also watched vivisection demonstrations by Ishii . From 1940 , Ishii was appointed Chief of the Biological Warfare Section of the Kwantung Army , holding the post simultaneously with that of the Bacteriological Department of the Army Medical Academy , and was promoted to surgeon major - general in March of the following year . In 1942 , Ishii began field tests of germ warfare agents developed , and various methods of dispersion ( e . g . via firearms , bombs etc . ) both on Chinese prisoners of war and operationally on battlefields and against civilians in Chinese cities . Some historians estimate that tens of thousands died as a result of the bio - weapons ( including bubonic plague , cholera , anthrax and others ) deployed . His unit also conducted physiological experiments on human subjects , including vivisection s , forced abortions , and simulated strokes , heart attacks , frostbite and hypothermia . From 1942 – 1945 , Ishii was Chief of the Medical Section of the Japanese First Army . He was promoted to surgeon lieutenant - general in March 1945 . In the final days of the Pacific War and in the face of imminent defeat , Japanese troops blew up the headquarters of Unit 731 in order to destroy evidence of the research done there . As part of the cover - up , Ishii ordered 150 remaining subjects killed . More than ten thousand people , from which around 600 every year were provided by the " kempeitai " ( Japanese secret police ) , were subjects of the experimentation conducted by Unit 731 . These were called by Ishii and his peers maruta ( 丸太 ) " logs , " a term originating either in the view of subjects as inert , expendable entities or possibly in the cover story told to locals that the facility contained a sawmill . Immunity . Arrested by the US occupation authorities at the end of World War II , Ishii and other Unit 731 leaders were to be thoroughly interrogated by the Soviet authorities . Instead Ishii and his team managed to negotiate and receive immunity in 1946 from war - crime s prosecution before the Tokyo tribunal in exchange for their full disclosure of germ warfare data based on human experimentation . Although the Soviet Russian authorities wished the prosecutions to take place , the USA objected after the reports of the investigating US microbiologists . Among these was Dr . Edwin Hill ( Chief of Fort Detrick ) , whose report stated that the information was " absolutely invaluable " , it " could never have been obtained in the USA because of scruples attached to experiments on humans " , and " the information was obtained fairly cheaply " . On 6 May 1947 , Douglas MacArthur wrote to Washington that " additional data , possibly some statements from Ishii probably can be obtained by informing Japanese involved that information will be retained in intelligence channels and will not be employed as ' War Crimes ' evidence . " The deal was concluded in 1948 . In this way Ishii was never prosecuted for any war crimes . Richard Drayton , a Cambridge University history lecturer , claimed that Ishii later went to Maryland to advise on bioweapon s . If Ishii did travel to Maryland , it was most likely to advise at Fort Detrick , a well known major biomedical experimentation facility in Frederick , Maryland . Another source says he stayed in Japan , where he opened a clinic where he did examinations and treatments for free . He was especially concerned with the health of children . In his final years he converted to Christianity . He kept a diary but it did not reference any of his wartime activity . He died of throat cancer at the age of 67 . Sources . Citations References